*551Chief Justice Rehnquist

delivered the opinion of the Court.

In the Gun-Free School Zones Act of 1990, Congress made it a federal offense “for any individual knowingly to possess a firearm at a place that the individual knows, or has reasonable cause to believe, is a school zone.” 18 U. S. C. § 922(q)(1)(A) (1988 ed., Supp. V). The Act neither regulates a commercial activity nor contains a requirement that the possession be connected in any way to interstate commerce. We hold that the Act exceeds the authority of Congress “[t]o regulate Commerce . . . among the several States . . . .” U. S. Const., Art. I, §8, cl. 3.

On March 10,1992, respondent, who was then a 12th~grade student, arrived at Edison High School in San Antonio, Texas, carrying a concealed .38-caliber handgun and five bullets. Acting upon an anonymous tip, school authorities confronted respondent, who admitted that he was carrying the weapon. He was arrested and charged under Texas law with firearm possession on school premises. See Tex. Penal Code Ann. § 46.03(a)(1) (Supp. 1994). The next day, the state charges were dismissed after federal agents charged respondent by complaint with violating the Gun-Free School Zones Act of 1990. 18 U. S. C. § 922(q)(1)(A) (1988 ed., Supp. V).1

A federal grand jury indicted respondent on one count of knowing possession of a firearm at a school zone, in violation of § 922(q). Respondent moved to dismiss his federal indictment on the ground that § 922(q) “is unconstitutional as it is beyond the power of Congress to legislate control over our public schools.” The District Court denied the motion, concluding that § 922(q) “is a constitutional exercise of Congress’ well-defined power to regulate activities in and affecting *552commerce, and the ‘business’ of elementary, middle and high schools . . . affects interstate commerce.” App. to Pet. for Cert. 55a. Respondent waived his right to a jury trial. The District Court conducted a bench trial, found him guilty of violating §922(q), and sentenced him to six months’ imprisonment and two years’ supervised release.

On appeal, respondent challenged his conviction based on his claim that § 922(q) exceeded Congress’ power to legislate under the Commerce Clause. The Court of Appeals for the Fifth Circuit agreed and reversed respondent’s conviction. It held that, in light of what it characterized as insufficient congressional findings and legislative history, “section 922(q), in the full reach of its terms, is invalid as beyond the power of Congress under the Commerce Clause.” 2 F. 3d 1342, 1367-1368 (1993). Because of the importance of the issue, we granted certiorari, 511 U. S. 1029 (1994), and we now affirm.

We start with first principles. The Constitution creates a Federal Government of enumerated powers. See Art. I, § 8. As James Madison wrote: “The powers delegated by the proposed Constitution to the federal government are few and defined. Those which are to remain in the State governments are numerous and indefinite.” The Federalist No. 45, pp. 292-293 (C. Rossiter ed. 1961). This constitutionally mandated division of authority “was adopted by the Framers to ensure protection of our fundamental liberties.” Gregory v. Ashcroft, 501 U. S. 452, 458 (1991) (internal quotation marks omitted). “Just as the separation and independence of the coordinate branches of the Federal Government serve to prevent the accumulation of excessive power in any one branch, a healthy balance of power between the States and the Federal Government will reduce the risk of tyranny and abuse from either front.” Ibid.

The Constitution delegates to Congress the power “[t]o regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes.” Art. I, §8, *553cl. 3. The Court, through Chief Justice Marshall, first defined the nature of Congress’ commerce power in Gibbons v. Ogden, 9 Wheat. 1, 189-190 (1824):

“Commerce, undoubtedly, is traffic, but it is something more: it is intercourse. It describes the commercial intercourse between nations, and parts of nations, in all its branches, and is regulated by prescribing rules for carrying on that intercourse.”

The commerce power “is the power to regulate; that is, to prescribe the rule by which commerce is to be governed. This power, like all others vested in congress, is complete in itself, may be exercised to its utmost extent, and acknowledges no limitations, other than are prescribed in the constitution.” Id., at 196. The Gibbons Court, however, acknowledged that limitations on the commerce power are inherent in the very language of the Commerce Clause.

“It is not intended to say that these words comprehend that commerce, which is completely internal, which is carried on between man and man in a State, or between different parts of the same State, and which does not extend to or affect other States. Such a power would be inconvenient, and is certainly unnecessary.

“Comprehensive as the word ‘among’ is, it may very properly be restricted to that commerce which concerns more States than one.... The enumeration presupposes something not enumerated; and that something, if we regard the language, or the subject of the sentence, must be the exclusively internal commerce of a State.” Id., at 194-195.

For nearly a century thereafter, the Court’s Commerce Clause decisions dealt but rarely with the extent of Congress’ power, and almost entirely with the Commerce Clause as a limit on state legislation that discriminated against interstate commerce. See, e. g., Veazie v. Moor, 14 How. 568, 573-575 (1853) (upholding a state-created steamboat monop*554oly because it involved regulation of wholly internal commerce); Kidd v. Pearson, 128 U. S. 1, 17, 20-22 (1888) (upholding a state prohibition on the manufacture of intoxicating liquor because the commerce power “does not comprehend the purely internal domestic commerce of a State which is carried on between man and man within a State or between different parts of the same State”); see also L. Tribe, American Constitutional Law 306 (2d ed. 1988). Under this line of precedent, the Court held that certain categories of activity such as “production,” “manufacturing,” and “mining” were within the province of state governments, and thus were beyond the power of Congress under the Commerce Clause. See Wickard v. Filburn, 317 U. S. 111, 121 (1942) (describing development of Commerce Clause jurisprudence).

In 1887, Congress enacted the Interstate Commerce Act, 24 Stat. 379, and in 1890, Congress enacted the Sherman Antitrust Act, 26 Stat. 209, as amended, 15 U. S. C. § 1 et seq. These laws ushered in a new era of federal regulation under the commerce power. When cases involving these laws first reached this Court, we imported from our negative Commerce Clause cases the approach that Congress could not regulate activities such as “production,” “manufacturing,” and “mining.” See, e. g., United States v. E. C. Knight Co., 156 U. S. 1, 12 (1895) (“Commerce succeeds to manufacture, and is not part of it”); Carter v. Carter Coal Co., 298 U. S. 238, 304 (1936) (“Mining brings the subject matter of commerce into existence. Commerce disposes of it”). Simultaneously, however, the Court held that, where the interstate and intrastate aspects of commerce were so mingled together that full regulation of interstate commerce required incidental regulation of intrastate commerce, the Commerce Clause authorized such regulation. See, e. g., Shreveport Rate Cases, 234 U. S. 342 (1914).

In A. L. A. Schechter Poultry Corp. v. United States, 295 U. S. 495, 550 (1935), the Court struck down regulations that *555fixed the hours and wages of individuals employed by an intrastate business because the activity being regulated related to interstate commerce only indirectly. In doing so, the Court characterized the distinction between direct and indirect effects of intrastate transactions upon interstate commerce as “a fundamental one, essential to the maintenance of our constitutional system.” Id., at 548. Activities that affected interstate commerce directly were within Congress’ power; activities that affected interstate commerce indirectly were beyond Congress’ reach. Id., at 546. The justification for this formal distinction was rooted in the fear that otherwise “there would be virtually no limit to the federal power and for all practical purposes we should have a completely centralized government.” Id., at 548.

Two years later, in the watershed case of NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1 (1937), the Court upheld the National Labor Relations Act against a Commerce Clause challenge, and in the process, departed from the distinction between “direct” and “indirect” effects on interstate commerce. Id., at 36-38 (“The question [of the scope of Congress’ power] is necessarily one of degree”). The Court held that intrastate activities that “have such a close and substantial relation to interstate commerce that their control is essential or appropriate to protect that commerce from burdens and obstructions” are within Congress’ power to regulate. Id., at 37.

In United States v. Darby, 312 U. S. 100 (1941), the Court upheld the Fair Labor Standards Act, stating:

“The power of Congress over interstate commerce is not confined to the regulation of commerce among the states. It extends to those activities intrastate which so affect interstate commerce or the exercise of the power of Congress over it as to make regulation of them appropriate means to the attainment of a legitimate end, the exercise of the granted power of Congress to regulate interstate commerce.” Id., at 118.

*556See also United States v. Wrightwood Dairy Co., 315 U. S. 110, 119 (1942) (the commerce power “extends to those intrastate activities which in a substantial way interfere with or obstruct the exercise of the granted power”).

In Wickard v. Filburn, the Court upheld the application of amendments to the Agricultural Adjustment Act of 1938 to the production and consumption of homegrown wheat. 317 U. S., at 128-129. The Wickard Court explicitly rejected earlier distinctions between direct and indirect effects on interstate commerce, stating:

“[Ejven if appellee’s activity be local and though it may not be regarded as commerce, it may still, whatever its nature, be reached by Congress if it exerts a substantial economic effect on interstate commerce, and this irrespective of whether such effect is what might at some earlier time have been defined as ‘direct’ or ‘indirect.’” Id., at 125.

The Wickard Court emphasized that although Filburn’s own contribution to the demand for wheat may have been trivial by itself, that was not “enough to remove him from the scope of federal regulation where, as here, his contribution, taken together with that of many others similarly situated, is far from trivial.” Id., at 127-128.

Jones & Laughlin Steel, Darby, and Wickard ushered in an era of Commerce Clause jurisprudence that greatly expanded the previously defined authority of Congress under that Clause. In part, this was a recognition of the great changes that had occurred in the way business was carried on in this country. Enterprises that had once been local or at most regional in nature had become national in scope. But the doctrinal change also reflected a view that earlier Commerce Clause cases artificially had constrained the authority of Congress to regulate interstate commerce.

But even these modern-era precedents which have expanded congressional power under the Commerce Clause *557confirm that this power is subject to outer limits. In Jones & Laughlin Steel, the Court warned that the scope of the interstate commerce power “must be considered in the light of our dual system of government and may not be extended so as to embrace effects upon interstate commerce so indirect and remote that to embrace them, in view of our complex society, would effectually obliterate the distinction between what is national and what is local and create a completely centralized government.” 301 U. S., at 37; see also Darby, supra, at 119-120 (Congress may regulate intrastate activity that has a “substantial effect” on interstate commerce); Wickard, supra, at 125 (Congress may regulate activity that “exerts a substantial economic effect on interstate commerce”). Since that time, the Court has heeded that warning and undertaken to decide whether a rational basis existed for concluding that a regulated activity sufficiently affected interstate commerce. See, e. g., Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S. 264, 276-280 (1981); Perez v. United States, 402 U. S. 146, 155-156 (1971); Katzenbach v. McClung, 379 U. S. 294, 299-301 (1964); Heart of Atlanta Motel, Inc. v. United States, 379 U. S. 241, 252-253 (1964).2

Similarly, in Maryland v. Wirtz, 392 U. S. 183 (1968), the Court reaffirmed that “the power to regulate commerce, though broad indeed, has limits” that “[t]he Court has ample power” to enforce. Id., at 196, overruled on other grounds, National League of Cities v. Usery, 426 U. S. 833 (1976), overruled by Garcia v. San Antonio Metropolitan Transit *558Authority, 469 U. S. 528 (1985). In response to the dissent’s warnings that the Court was powerless to enforce the limitations on Congress’ commerce powers because “[a]ll activities affecting commerce, even in the minutest degree, [Wickard], may be regulated and controlled by Congress,” 392 U. S., at 204 (Douglas, J., dissenting), the Wirtz Court replied that the dissent had misread precedent as “[njeither here nor in Wickard has the Court declared that Congress may use a relatively trivial impact on commerce as an excuse for broad general regulation of state or private activities,” id., at 197, n. 27. Rather, “[t]he Court has said only that where a general regulatory statute bears a substantial relation to commerce, the de minimis character of individual instances arising under that statute is of no consequence.” Ibid, (first emphasis added).

Consistent with this structure, we have identified three broad categories of activity that Congress may regulate under its commerce power. Perez, supra, at 150; see also Hodel, supra, at 276-277. First, Congress may regulate the use of the channels of interstate commerce. See, e.g., Darby, 312 U. S., at 114; Heart of Atlanta Motel, supra, at 256 (“ ‘[T]he authority of Congress to keep the channels of interstate commerce free from immoral and injurious uses has been frequently sustained, and is no longer open to question’ ” (quoting Caminetti v. United States, 242 U. S. 470, 491 (1917))). Second, Congress is empowered to regulate and protect the instrumentalities of interstate commerce, or persons or things in interstate commerce, even though the threat may come only from intrastate activities. See, e. g., Shreveport Rate Cases, 234 U. S. 342 (1914); Southern R. Co. v. United States, 222 U. S. 20 (1911) (upholding amendments to Safety Appliance Act as applied to vehicles used in intrastate commerce); Perez, supra, at 150 (“[F]or example, the destruction of an aircraft (18 U. S. C. § 32), or... thefts from interstate shipments (18 U. S. C. § 659)”). Finally, Congress’ commerce authority includes the power to regulate those ac*559tivities having a substantial relation to interstate commerce, Jones & Laughlin Steel, 301 U. S., at 37, i. e., those activities that substantially affect interstate commerce, Wirtz, supra, at 196, n. 27.

Within this final category, admittedly, our case law has not been clear whether an activity must “affect” or “substantially affect” interstate commerce in order to be within Congress’ power to regulate it under the Commerce Clause. Compare Preseault v. ICC, 494 U. S. 1, 17 (1990), with Wirtz, supra, at 196, n. 27 (the Court has never declared that “Congress may use a relatively trivial impact on commerce as an excuse for broad general regulation of state or private activities”). We conclude, consistent with the great weight of our case law, that the proper test requires an analysis of whether the regulated activity “substantially affects” interstate commerce.

We now turn to consider the power of Congress, in the light of this framework, to enact § 922(q). The first two categories of authority may be quickly disposed of: § 922(q) is not a regulation of the use of the channels of interstate commerce, nor is it an attempt to prohibit the interstate transportation of a commodity through the channels of commerce; nor can § 922(q) be justified as a regulation by which Congress has sought to protect an instrumentality of interstate commerce or a thing in interstate commerce. Thus, if § 922(q) is to be sustained, it must be under the third category as a regulation of an activity that substantially affects interstate commerce.

First, we have upheld a wide variety of congressional Acts regulating intrastate economic activity where we have concluded that the activity substantially affected interstate commerce. Examples include the regulation of intrastate coal mining; Hodel, supra, intrastate extortionate credit transactions, Perez, supra, restaurants utilizing substantial interstate supplies, McClung, supra, inns and hotels catering to interstate guests, Heart of Atlanta Motel, supra, and pro*560duction and consumption of homegrown wheat, Wickard v. Filburn, 317 U. S. 111 (1942). These examples are by no means exhaustive, but the pattern is clear. Where economic activity substantially affects interstate commerce, legislation regulating that activity will be sustained.

Even Wickard, which is perhaps the most far reaching example of Commerce Clause authority over intrastate activity, involved economic activity in a way that the possession of a gun in a school zone does not. Roscoe Filburn operated a small farm in Ohio, on which, in the year involved, he raised 23 acres of wheat. It was his practice to sow winter wheat in the fall, and after harvesting it in July to sell a portion of the crop, to feed part of it to poultry and livestock on the farm, to use some in making flour for home consumption, and to keep the remainder for seeding future crops. The Secretary of Agriculture assessed a penalty against him under the Agricultural Adjustment Act of 1938 because he harvested about 12 acres more wheat than his allotment under the Act permitted. The Act was designed to regulate the volume of wheat moving in interstate and foreign commerce in order to avoid surpluses and shortages, and concomitant fluctuation in wheat prices, which had previously obtained. The Court said, in an opinion sustaining the application of the Act to Filburn’s activity:

“One of the primary purposes of the Act in question was to increase the market price of wheat and to that end to limit the volume thereof that could affect the market. It can hardly be denied that a factor of such volume and variability as home-consumed wheat would have a substantial influence on price and market conditions. This may arise because being in marketable condition such wheat overhangs the market and, if induced by rising prices, tends to flow into the market and check price increases. But if we assume that it is never marketed, it supplies a need of the man who grew it which would otherwise be reflected by purchases in the open market. *561Home-grown wheat in this sense competes with wheat in commerce.” 317 U. S., at 128.

Section 922(q) is a criminal statute that by its terms has nothing to do with “commerce” or any sort of economic enterprise, however broadly one might define those terms.3 Section 922(q) is not an essential part of a larger regulation of economic activity, in which the regulatory scheme could be undercut unless the intrastate activity were regulated. It cannot, therefore, be sustained under our cases upholding regulations of activities that arise out of or are connected with a commercial transaction, which viewed in the aggregate, substantially affects interstate commerce.

Second, § 922(q) contains no jurisdictional element which would ensure, through case-by-case inquiry, that the firearm possession in question affects interstate commerce. For example, in United States v. Bass, 404 U. S. 336 (1971), the Court interpreted former 18 U. S. C. § 1202(a), which made it *562a crime for a felon to “receiv[e], posses[s], or transport] in commerce or affecting commerce . . . any firearm.” 404 U. S., at 337. The Court interpreted the possession component of § 1202(a) to require an additional nexus to interstate commerce both because the statute was ambiguous and because “unless Congress conveys its purpose clearly, it will not be deemed to have significantly changed the federal-state balance.” Id., at 349. The Bass Court set aside the conviction because, although the Government had demonstrated that Bass had possessed a firearm, it had failed “to show the requisite nexus with interstate commerce.” Id., at 347. The Court thus interpreted the statute to reserve the constitutional question whether Congress could regulate, without more, the “mere possession” of firearms. See id., at 339, n. 4; see also United States v. Five Gambling Devices, 346 U. S. 441, 448 (1953) (plurality opinion) (“The principle is old and deeply imbedded in our jurisprudence that this Court will construe a statute in a manner that requires decision of serious constitutional questions only if the statutory language leaves no reasonable alternative”). Unlike the statute in Bass, §922(q) has no express jurisdictional element which might limit its reach to a discrete set of firearm possessions that additionally have an explicit connection with or effect on interstate commerce.

Although as part of our independent evaluation of constitutionality under the Commerce Clause we of course consider legislative findings, and indeed even congressional committee findings, regarding effect on interstate commerce, see, e. g., Preseault v. ICC, 494 U. S., at 17, the Government concedes that “[njeither the statute nor its legislative history contain[s] express congressional findings regarding the effects upon interstate commerce of gun possession in a school zone.” Brief for United States 5-6. We agree with the Government that Congress normally is not required to make formal findings as to the substantial burdens that an activity has on interstate commerce. See McClung, 379 U. S., at 304; *563see also Perez, 402 U. S., at 156 (“Congress need [not] make particularized findings in order to legislate”). But to the extent that congressional findings would enable us to evaluate the legislative judgment that the activity in question substantially affected interstate commerce, even though no such substantial effect was visible to the naked eye, they are lacking here.4

The Government argues that Congress has accumulated institutional expertise regarding the regulation of firearms through previous enactments. Cf. Fullilove v. Klutznick, 448 U. S. 448, 503 (1980) (Powell, J., concurring). We agree, however, with the Fifth Circuit that importation of previous findings to justify §922(q) is especially inappropriate here because the “prior federal enactments or Congressional findings [do not] speak to the subject matter of section 922(q) or its relationship to interstate commerce. Indeed, section 922(q) plows thoroughly new ground and represents a sharp break with the long-standing pattern of federal firearms legislation.” 2 F. 3d, at 1366.

The Government’s essential contention, in fine, is that we may determine here that § 922(q) is valid because possession of a firearm in a local school zone does indeed substantially affect interstate commerce. Brief for United States 17. The Government argues that possession of a firearm in a school zone may result in violent crime and that violent crime can be expected to affect the functioning of the national economy in two ways. First, the costs of violent *564crime are substantial, and, through the mechanism of insurance, those costs are spread throughout the population. See United States v. Evans, 928 F. 2d 858, 862 (CA9 1991). Second, violent crime reduces the willingness of individuals to travel to areas within the country that are perceived to be unsafe. Cf. Heart of Atlanta Motel, 379 U. S., at 253. The Government also argues that the presence of guns in schools poses a substantial threat to the educational process by threatening the learning environment. A handicapped educational process, in turn, will result in a less productive citizenry. That, iii turn, would have an adverse effect on the Nation’s economic well-being. As a result, the Government argues that Congress could rationally have concluded that § 922(q) substantially affects interstate commerce.

We pause to consider the implications of the Government’s arguments. The Government admits, under its “costs of crime” reasoning, that Congress could regulate not only all violent crime, but all activities that might lead to violent crime, regardless of how tenuously they relate to interstate commerce. See Tr. of Oral Arg. 8-9. Similarly, under the Government’s “national productivity” reasoning, Congress could regulate any activity that it found was related to the economic productivity of individual citizens: family law (including marriage, divorce, and child custody), for example. Under the theories that the Government presents in support of § 922(q), it is difficult to perceive any limitation on federal power, even in areas such as criminal law enforcement or education where States historically have been sovereign. Thus, if we were to accept the Government’s arguments, we are hard pressed to posit any activity by an individual that Congress is' without power to regulate.

Although Justice Breyer argues that acceptance of the Government’s rationales would not authorize a general federal police power, he is unable to identify any activity that the States may regulate but Congress may not. Justice Breyer posits that there might be some limitations on Con*565gress’ commerce power, such as family law or certain aspects of education. Post, at 624. These suggested limitations, when viewed in light of the dissent’s expansive analysis, are devoid of substance.

Justice Breyer focuses, for the most part, on the threat that firearm possession in and near schools poses to the educational process and the potential economic consequences flowing from that threat. Post, at 619-624. Specifically, the dissent reasons that (1) gun-related violence is a serious problem; (2) that problem, in turn, has an adverse effect on classroom learning; and (3) that adverse effect on classroom learning, in turn, represents a substantial threat to trade and commerce. Post, at 623. This analysis would be equally applicable, if not more so, to subjects such as family law and direct regulation of education.

For instance, if Congress can, pursuant to its Commerce Clause power, regulate activities that adversely affect the learning environment, then, a fortiori, it also can regulate the educational process directly. Congress could determine that a school’s curriculum has a “significant” effect on the extent of classroom learning. As a result, Congress could mandate a federal curriculum for local elementary and secondary schools because what is taught in local schools has a significant “effect on classroom learning,” cf. ibid., and that, in turn, has a substantial effect on interstate commerce.

Justice Breyer rejects our reading of precedent and argues that “Congress . . . could rationally conclude that schools fall on the commercial side of the line.” Post, at 629. Again, Justice Breyer’s rationale lacks any real limits because, depending on the level of generality, any activity can be looked upon as commercial. Under the dissent’s rationale, Congress could just as easily look at child rearing as “fall[ing] on the commercial side of the line” because it provides a “valuable service — namely, to equip [children] with the skills they need to survive in life and, more specifically, in the workplace.” Ibid. We do not doubt that Congress *566has authority under the Commerce Clause to regulate numerous commercial activities that substantially affect interstate commerce and also affect the educational process. That authority, though broad, does not include the authority to regulate each and every aspect of local schools.

Admittedly, a determination whether an intrastate activity is commercial or noncommercial may in some eases result in legal uncertainty. But, so long as Congress’ authority is limited to those powers enumerated in the Constitution, and so long as those enumerated powers are interpreted as having judicially enforceable outer limits, congressional legislation under the Commerce Clause always will engender “legal uncertainty.” Post, at 630. As Chief Justice Marshall stated in McCulloch v. Maryland, 4 Wheat. 316 (1819):

“Th[e] [federal] government is acknowledged by all to be one of enumerated powers. The principle, that it can exercise only the powers granted to it... is now universally admitted. But the question respecting the extent of the powers actually granted, is perpetually arising, and will probably continue to arise, as long as our system shall exist.” Id., at 405.

See also Gibbons v. Ogden, 9 Wheat., at 195 (“The enumeration presupposes something not enumerated”). The Constitution mandates this uncertainty by withholding from Congress a plenary police power that would authorize enactment of every type of legislation. See Art. I, § 8. Congress has operated within this framework of legal uncertainty ever since this Court determined that it was the Judiciary’s duty “to say what the law is.” Marbury v. Madison, 1 Cranch 137, 177 (1803) (Marshall, C. J.). Any possible benefit from eliminating this “legal uncertainty” would be at the expense of the Constitution’s system of enumerated powers.

In Jones & Laughlin Steel, 301 U. S., at 37, we held that the question of congressional power under the Commerce Clause “is necessarily one of degree.” To the same effect *567is the concurring opinion of Justice Cardozo in Schechter Poultry:

“There is a view of causation that would obliterate the distinction between what is national and what is local in the activities of commerce. Motion at the outer rim is communicated perceptibly, though minutely, to recording instruments at the center. A society such as ours ‘is an elastic medium which transmits all tremors throughout its territory; the only question is of their size.’” 295 U. S., at 554 (quoting United States v. A. L. A. Schechter Poultry Corp., 76 F. 2d 617, 624 (CA2 1935) (L. Hand, J., concurring)).

These are not precise formulations, and in the nature of things they cannot be. But we think they point the way to a correct decision of this case. The possession of a gun in a local school zone is in no sense an economic activity that might, through repetition elsewhere, substantially affect any sort of interstate commerce. Respondent was a local student at a local school; there is no indication that he had recently moved in interstate commerce, and there is no requirement that his possession of the firearm have any concrete tie to interstate commerce.

To uphold the Government’s contentions here, we would have to pile inference upon inference in a manner that would bid fair to convert congressional authority under the Commerce Clause to a general police power of the sort retained by the States. Admittedly, some of our prior cases have taken long steps down that road, giving great deference to congressional action. See supra, at 556-558. The broad language in these opinions has suggested the possibility of additional expansion, but we decline here to proceed any further. To do so would require us to conclude that the Constitution’s enumeration of powers does not presuppose something not enumerated, cf. Gibbons v. Ogden, supra, at 195, and that there never will be a distinction between what is *568truly national and what is truly local, cf. Jones & Laughlin Steel, supra, at 30. This we are unwilling to do.

For the foregoing reasons the judgment of the Court of Appeals is

Affirmed.

Justice Kennedy,

with whom Justice O’Connor joins,

concurring.

The history of the judicial struggle to interpret the Commerce Clause during the transition from the economic system the Founders knew to the single, national market still emergent in our own era counsels great restraint before the Court determines that the Clause is insufficient to support an exercise of the national power. That history gives me some pause about today’s decision, but I join the Court’s opinion with these observations on what I conceive to be its necessary though limited holding.

Chief Justice Marshall announced that the national authority reaches “that commerce which concerns more States than one” and that the commerce power “is complete in itself, may be exercised to its utmost extent, and acknowledges no limitations, other than are prescribed in the constitution.” Gibbons v. Ogden, 9 Wheat. 1, 194, 196 (1824). His statements can be understood now as an early and authoritative recognition that the Commerce Clause grants Congress extensive power and ample discretion to determine its appropriate exercise. The progression of our Commerce Clause cases from Gibbons to the present was not marked, however, by a coherent or consistent course of interpretation; for neither the course of technological advance nor the foundational principles for the jurisprudence itself were self-evident to the courts that sought to resolve contemporary disputes by enduring principles.

Furthermore, for almost a century after the adoption of the Constitution, the Court’s Commerce Clause decisions did not concern the authority of Congress to legislate. Rather, *569the Court faced the related but quite distinct question of the authority of the States to regulate matters that would be within the commerce power had Congress chosen to act. The simple fact was that in the early years of the Republic, Congress seldom perceived the necessity to exercise its power in circumstances where its authority would be called into question. The Court’s initial task, therefore, was to elaborate the theories that would permit the States to act where Congress had not done so. Not the least part of the problem was the unresolved question whether the congressional power was exclusive, a question reserved by Chief Justice Marshall in Gibbons v. Ogden, supra, at 209-210.

At the midpoint of the 19th century, the Court embraced the principle that the States and the National Government both have authority to regulate certain matters absent the congressional determination to displace local law or the necessity for the Court to invalidate local law because of the dormant national power. Cooley v. Board of Wardens of Port of Philadelphia ex rel. Soc. for Relief of Distressed Pilots, 12 How. 299, 318-321 (1852). But the utility of that solution was not at once apparent, see generally F. Frankfurter, The Commerce Clause under Marshall, Taney and Waite (1937) (hereinafter Frankfurter), and difficulties of application persisted, see Leisy v. Hardin, 135 U. S. 100, 122-125 (1890).

One approach the Court used to inquire into the lawfulness of state authority was to draw content-based or subject-matter distinctions, thus defining by semantic or formalistic categories those activities that were commerce and those that were not. For instance, in deciding that a State could prohibit the in-state manufacture of liquor intended for out-of-state shipment, it distinguished between manufacture and commerce. “No distinction is more popular to the common mind, or more clearly expressed in economic and political literature, than that between manufacture] and commerce. Manufacture is transformation — the fashioning of raw mate*570rials into a change of form for use. The functions of commerce are different.” Kidd v. Pearson, 128 U. S. 1, 20 (1888). Though that approach likely would not have survived even if confined to the question of a State’s authority to enact legislation, it was not at all propitious when applied to the quite different question of what subjects were within the reach of the national power when Congress chose to exercise it.

This became evident when the Court began to confront federal economic regulation enacted in response to the rapid industrial development in the late 19th century. Thus, it relied upon the manufacture-commerce dichotomy in United States v. E. C. Knight Co., 156 U. S. 1 (1895), where a manufacturers’ combination controlling some 98% of the Nation’s domestic sugar refining capacity was held to be outside the reach of the Sherman Act. Conspiracies to control manufacture, agriculture, mining, production, wages, or prices, the Court explained, had too “indirect” an effect on interstate commerce. Id., at 16. And in Adair v. United States, 208 U. S. 161 (1908), the Court rejected the view that the commerce power might extend to activities that, although local in the sense of having originated within a single State, nevertheless had a practical effect on interstate commercial activity. The Court concluded that there was not a “legal or logical connection . .. between an employé’s membership in a labor organization and the carrying on of interstate commerce,” id., at 178, and struck down a federal statute forbidding the discharge of an employee because of his membership in a labor organization. See also The Employers’ Liability Cases, 207 U. S. 468, 497 (1908) (invalidating statute creating negligence action against common carriers for personal injuries of employees sustained in the course of employment, because the statute “regulates the persons because they engage in interstate commerce and does not alone regulate the business of interstate commerce”).

*571Even before the Court committed itself to sustaining federal legislation on broad principles of economic practicality, it found it necessary to depart from these decisions. The Court disavowed E. C. Knight’s reliance on the manufacturing-commerce distinction in Standard Oil Co. of N. J. v. United States, 221 U. S. 1, 68-69 (1911), declaring that approach “unsound.” The Court likewise rejected the rationale of Adair when it decided, in Texas & New Orleans R. Co. v. Railway Clerks, 281 U. S. 548, 570-571 (1930), that Congress had the power to regulate matters pertaining to the organization of railroad workers.

In another line of cases, the Court addressed Congress’ efforts to impede local activities it considered undesirable by prohibiting the interstate movement of some essential element. In the Lottery Case, 188 U. S. 321 (1903), the Court rejected the argument that Congress lacked power to prohibit the interstate movement of lottery tickets because it had power only to regulate, not to prohibit. See also Hipolite Egg Co. v. United States, 220 U. S. 45 (1911); Hoke v. United States, 227 U. S. 308 (1913). In Hammer v. Dagenhart, 247 U. S. 251 (1918), however, the Court insisted that the power to regulate commerce “is directly the contrary of the assumed right to forbid commerce from moving,” id., at 269-270, and struck down a prohibition on the interstate transportation of goods manufactured in violation of child labor laws.

Even while it was experiencing difficulties in finding satisfactory principles in these cases, the Court was pursuing a more sustainable and practical approach in other lines of decisions, particularly those involving the regulation of railroad rates. In the Minnesota Rate Cases, 230 U. S. 352 (1913), the Court upheld a state rate order, but observed that Congress might be empowered to regulate in this area if “by reason of the interblending of the interstate and intrastate operations of interstate carriers” the regulation of interstate rates could not be maintained without restrictions on “intra*572state rates which substantially affect the former.” Id., at 432-433. And in the Shreveport Rate Cases, 234 U. S. 342 (1914), the Court upheld an Interstate Commerce Commission order fixing railroad rates with the explanation that congressional authority, “extending to these interstate carriers as instruments of interstate commerce, necessarily embraces the right to control their operations in all matters having such a close and substantial relation to interstate traffic that the control is essential or appropriate to the security of that traffic, to the efficiency of the interstate service, and to the maintenance of conditions under which interstate commerce may be conducted upon fair terms and without molestation or hindrance.” Id., at 351.

Even the most confined interpretation of “commerce” would embrace transportation between the States, so the rate cases posed much less difficulty for the Court than cases involving manufacture or production. Nevertheless, the Court’s recognition of the importance of a practical conception of the commerce power was not altogether confined to the rate cases. In Swift & Co. v. United States, 196 U. S. 375 (1905), the Court upheld the application of federal antitrust law to a combination of meat dealers that occurred in one State but that restrained trade in cattle “sent for sale from a place in one State, with the expectation that they will end their transit ... in another.” Id., at 398. The Court explained that “commerce among the States is not a technical legal conception, but a practical one, drawn from the course of business.” Ibid. Chief Justice Taft followed the same approach in upholding federal regulation of stockyards in Stafford v. Wallace, 258 U. S. 495 (1922). Speaking for the Court, he rejected a “nice and technical inquiry,” id., at 519, when the local transactions at issue could not “be separated from the movement to which they contribute,” id., at 516.

Reluctance of the Court to adopt that approach in all of its cases caused inconsistencies in doctrine to persist, however. In addressing New Deal legislation the Court resuscitated *573the abandoned abstract distinction between direct and indirect effects on interstate commerce. See Carter v. Carter Coal Co., 298 U. S. 238, 309 (1936) (Act regulating price of coal and wages and hours for miners held to have only “secondary and indirect” effect on interstate commerce); Railroad Retirement Bd. v. Alton R. Co., 295 U. S. 330, 368 (1935) (compulsory retirement and pension plan for railroad carrier employees too “remote from any regulation of commerce as such”); A. L. A. Schechter Poultry Corp. v. United States, 295 U. S. 495, 548 (1935) (wage and hour law provision of National Industrial Recovery Act had “no direct relation to interstate commerce”).

The case that seems to mark the Court’s definitive commitment to the practical conception of the commerce power is NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1 (1937), where the Court sustained labor laws that applied to manufacturing facilities, making no real attempt to distinguish Carter, supra, and Schechter, supra. 301 U. S., at 40-41. The deference given to Congress has since been confirmed. United States v. Darby, 312 U. S. 100, 116-117 (1941), overruled Hammer v. Dagenhart, supra. And in Wickard v. Filburn, 317 U. S. 111 (1942), the Court disapproved E. C. Knight and the entire line of direct-indirect and manufacture-production cases, explaining that “broader interpretations of the Commerce Clause [were] destined to supersede the earlier ones,” 317 U. S., at 122, and “[w]hatever terminology is used, the criterion is necessarily one of degree and must be so defined. This does not satisfy those who seek mathematical or rigid formulas. But such formulas are not provided by the great concepts of the Constitution,” id., at 123, n. 24. Later examples of the exercise of federal power where commercial transactions were the subject of regulation include Heart of Atlanta Motel, Inc. v. United States, 379 U. S. 241 (1964), Katzenbach v. McClung, 379 U. S. 294 (1964), and Perez v. United States, 402 U. S. 146 (1971). These and like authorities are within the fair ambit *574of the Court’s practical conception of commercial regulation and are not called in question by our decision today.

The history of our Commerce Clause decisions contains at least two lessons of relevance to this case. The first, as stated at the outset, is the imprecision of content-based boundaries used without more to define the limits of the Commerce Clause. The second, related to the first but of even greater consequence, is that the Court as an institution and the legal system as a whole have an immense stake in the stability of our Commerce Clause jurisprudence as it has evolved to this point. Stare decisis operates with great force in counseling us not to call in question the essential principles now in place respecting the congressional power to regulate transactions of a commercial nature. That fundamental restraint on our power forecloses us from reverting to an understanding of commerce that would serve only an 18th-century economy, dependent then upon production and trading practices that had changed but little over the preceding centuries; it also mandates against returning to the time when congressional authority to regulate undoubted commercial activities was limited by a judicial determination that those matters had an insufficient connection to an interstate system. Congress can regulate in the commercial sphere on the assumption that we have a single market and a unified purpose to build a stable national economy.

In referring to the whole subject of the federal and state balance, we said this just three Terms ago:

“This framework has been sufficiently flexible over the past two centuries to allow for enormous changes in the nature of government. The Federal Government undertakes activities today that would have been unimaginable to the Framers in two senses: first, because the Framers would not have conceived that any government would conduct such activities; and second, because the Framers would not have believed that the Federal Government, rather than the States, would assume such *575responsibilities. Yet the powers conferred upon the Federal Government by the Constitution were phrased in language broad enough to allow for the expansion of the Federal Government’s role.” New York v. United States, 505 U. S. 144, 157 (1992) (emphasis deleted).

It does not follow, however, that in every instance the Court lacks the authority and responsibility to review congressional attempts to alter the federal balance. This case requires us to consider our place in the design of the Government and to appreciate the significance of federalism in the whole structure of the Constitution.

Of the various structural elements in the Constitution, separation of powers, checks and balances, judicial review, and federalism, only concerning the last does there seem to be much uncertainty respecting the existence, and the content, of standards that allow the Judiciary to play a significant role in maintaining the design contemplated by the Framers. Although the resolution of specific cases has proved difficult, we have derived from the Constitution workable standards to assist in preserving separation of powers and checks and balances. See, e. g., Prize Cases, 2 Black 635 (1863); Youngstown Sheet & Tube Co. v. Sawyer, 343 U. S. 579 (1952); United States v. Nixon, 418 U. S. 683 (1974); Buckley v. Valeo, 424 U. S. 1 (1976); INS v. Chadha, 462 U. S. 919 (1983); Bowsher v. Synar, 478 U. S. 714 (1986); Plaut v. Spendthrift Farm, Inc., ante, p. 211. These standards are by now well accepted. Judicial review is also established beyond question, Marbury v. Madison, 1 Cranch 137 (1803), and though we may differ when applying its principles, see, e. g., Planned Parenthood of Southeastern Pa. v. Casey, 505 U. S. 833 (1992), its legitimacy is undoubted. Our role in preserving the federal balance seems more tenuous.

There is irony in this, because of the four structural elements in the Constitution just mentioned, federalism was the unique contribution of the Framers to political science and political theory. See Friendly, Federalism: A Foreword, 86 *576Yale L. J. 1019 (1977); G. Wood, The Creation of the American Republic, 1776-1787, pp. 524-532, 564 (1969). Though on the surface the idea may seem counterintuitive, it was the insight of the Framers that freedom was enhanced by the creation of two governments, not one. “In the compound republic of America, the power surrendered by the people is first divided between two distinct governments, and then the portion allotted to each subdivided among distinct and separate departments. Hence a double security arises to the rights of the people. The different governments will control each other, at the same time that each will be controlled by itself.” The Federalist No. 51, p. 323 (C. Rossiter ed. 1961) (J. Madison). See also Gregory v. Ashcroft, 501 U. S. 452, 458-459 (1991) (“Just as the separation and independence of the coordinate branches of the Federal Government serve to prevent the accumulation of excessive power in any one branch, a healthy balance of power between the States and the Federal Government will reduce the risk of tyranny and abuse from either front. ... In the tension between federal and state power lies the promise of liberty”); New York v. United States, supra, at 181 (“[T]he Constitution divides authority between federal and state governments for the protection of individuals. State sovereignty is not just an end in itself: ‘Rather, federalism secures to citizens the liberties that derive from the diffusion of sovereign power’ ”) (quoting Coleman v. Thompson, 501 U. S. 722, 759 (1991) (Blackmun, J., dissenting)).

The theory that two governments accord more liberty than one requires for its realization two distinct and discern-able lines of political accountability: one between the citizens and the Federal Government; the second between the citizens and the States. If, as Madison expected, the Federal and State Governments are to control each other, see The Federalist No. 51, and hold each other in check by competing for the affections of the people, see The Federalist No. 46, those citizens must have some means of knowing which of *577the two governments to hold accountable for the failure to perform a given function. “Federalism serves to assign political responsibility, not to obscure it.” FTC v. Ticor Title Ins. Co., 504 U. S. 621, 636 (1992). Were the Federal Government to take over the regulation of entire areas of traditional state concern, areas having nothing to do with the regulation of commercial activities, the boundaries between the spheres of federal and state authority would blur and political responsibility would become illusory. Cf. New York v. United States, supra, at 155-169; FERC v. Mississippi, 456 U. S. 742, 787 (1982) (O’Connor, J., concurring in judgment in part and dissenting in part). The resultant inability to hold either branch of the government answerable to the citizens is more dangerous even than devolving too much authority to the remote central power.

To be sure, one conclusion that could be drawn from The Federalist Papers is that the balance between national and state power is entrusted in its entirety to the political process. Madison’s observation that “the people ought not surely to be precluded from giving most of their confidence where they may discover it to be most due,” The Federalist No. 46, p. 295 (C. Rossiter ed. 1961), can be interpreted to say that the essence of responsibility for a shift in power from the State to the Federal Government rests upon a political judgment, though he added assurance that “the State governments could have little to apprehend, because it is only within a certain sphere that the federal power can, in the nature of things, be advantageously administered,” ibid. Whatever the judicial role, it is axiomatic that Congress does have substantial discretion and control over the federal balance.

For these reasons, it would be mistaken and mischievous for the political branches to forget that the sworn obligation to preserve and protect the Constitution in maintaining the federal balance is their own in the first and primary instance. In the Webster-Hayne Debates, see The Great Speeches and *578Orations of Daniel Webster 227-272 (E. Whipple ed. 1879), and the debates over the Civil Rights Acts, see Hearings on S. 1732 before the Senate Committee on Commerce, 88th Cong., 1st Sess., pts. 1-3 (1963), some Congresses have accepted responsibility to confront the great questions of the proper federal balance in terms of lasting consequences for the constitutional design. The political branches of the Government must fulfill this grave constitutional obligation if democratic liberty and the federalism that secures it are to endure.

At the same time, the absence of structural mechanisms to require those officials to undertake this principled task, and the momentary political convenience often attendant upon their failure to do so, argue against a complete renunciation of the judicial role. Although it is the obligation of all officers of the Government to respect the constitutional design, see Public Citizen v. Department of Justice, 491 U. S. 440, 466 (1989); Rostker v. Goldberg, 453 U. S. 57, 64 (1981), the federal balance is too essential a part of our constitutional structure and plays too vital a role in securing freedom for us to admit inability to intervene when one or the other level of Government has tipped the scales too far.

In the past this Court has participated in maintaining the federal balance through judicial exposition of doctrines such as abstention, see, e. g., Younger v. Harris, 401 U. S. 37 (1971); Railroad Comm’n of Tex. v. Pullman Co., 312 U. S. 496 (1941); Burford v. Sun Oil Co., 319 U. S. 315 (1943), the rules for determining the primacy of state law, see, e. g., Erie R. Co. v. Tompkins, 304 U. S. 64 (1938), the doctrine of adequate and independent state grounds, see, e. g., Murdock v. Memphis, 20 Wall. 590 (1875); Michigan v. Long, 463 U. S. 1032 (1983), the whole jurisprudence of pre-emption, see, e. g., Rice v. Santa Fe Elevator Corp., 331 U. S. 218 (1947); Cipollone v. Liggett Group, Inc., 505 U. S. 504 (1992), and many of the rules governing our habeas jurisprudence, see, e. g., Coleman v. Thompson, 501 U. S. 722 (1991); McCleskey *579v. Zant, 499 U. S. 467 (1991); Teague v. Lane, 489 U. S. 288 (1989); Rose v. Lundy, 455 U. S. 509 (1982); Wainwright v. Sykes, 433 U. S. 72 (1977).

Our ability to preserve this principle under the Commerce Clause has presented a much greater challenge. See supra, at 568-574. “This clause has throughout the Court’s history been the chief source of its adjudications regarding federalism,” and “no other body of opinions affords a fairer or more revealing test of judicial qualities.” Frankfurter 66-67. But as the branch whose distinctive duty it is to declare “what the law is,” Marbury v. Madison, 1 Cranch, at 177, we are often called upon to resolve questions of constitutional law not susceptible to the mechanical application of bright and clear lines. The substantial element of political judgment in Commerce Clause matters leaves our institutional capacity to intervene more in doubt than when we decide cases, for instance, under the Bill of Rights even though clear and bright lines are often absent in the latter class of disputes. See County of Allegheny v. American Civil Liberties Union, Greater Pittsburgh Chapter, 492 U. S. 573, 630 (1989) (O’Connor, J., concurring in part and concurring in judgment) (“We cannot avoid the obligation to draw lines, often close and difficult lines” in adjudicating constitutional rights). But our cases do not teach that we have no role at all in determining the meaning of the Commerce Clause.

Our position in enforcing the dormant Commerce Clause is instructive. The Court’s doctrinal approach in that area has likewise “taken some turns.” Oklahoma Tax Comm’n v. Jefferson Lines, Inc., ante, at 180. Yet in contrast to the prevailing skepticism that surrounds our ability to give meaning to the explicit text of the Commerce Clause, there is widespread acceptance of our authority to enforce the dormant Commerce Clause, which we have but inferred from the constitutional structure as a limitation on the power of the States. One element of our dormant Commerce Clause jurisprudence has been the principle that the States may not *580impose regulations that place an undue burden on interstate commerce, even where those regulations do not discriminate between in-state and out-of-state businesses. See Brown-Forman Distillers Corp. v. New York State Liquor Authority, 476 U. S. 578, 579 (1986) (citing Pike v. Bruce Church, Inc., 397 U. S. 137, 142 (1970)). Distinguishing between regulations that do place an undue burden on interstate commerce and regulations that do not depends upon delicate judgments. True, if we invalidate a state law, Congress can in effect overturn our judgment, whereas in a case announcing that Congress has transgressed its authority, the decision is more consequential, for it stands unless Congress can revise its law to demonstrate its commercial character. This difference no doubt informs the circumspection with which we invalidate an Act of Congress, but it does not mitigate our duty to recognize meaningful limits on the commerce power of Congress.

The statute before us upsets the federal balance to a degree that renders it an unconstitutional assertion of the commerce power, and our intervention is required. As The Chief Justice explains, unlike the earlier cases to come before the Court here neither the actors nor their conduct has a commercial character, and neither the purposes nor the design of the statute has an evident commercial nexus. See ante, at 559-561. The statute makes the simple possession of a gun within 1,000 feet of the grounds of the school a criminal offense. In a sense any conduct in this interdependent world of ours has an ultimate commercial origin or consequence, but we have not yet said the commerce power may reach so far. If Congress attempts that extension, then at the least we must inquire whether the exercise of national power seeks to intrude upon an area of traditional state concern.

An interference of these dimensions occurs here, for it is well established that education is a traditional concern of the States. Milliken v. Bradley, 418 U. S. 717, 741-742 (1974); *581Epperson v. Arkansas, 393 U. S. 97, 104 (1968). The proximity to schools, including of course schools owned and operated by the States or their subdivisions, is the very premise for making the conduct criminal. In these circumstances, we have a particular duty to ensure that the federal-state balance is not destroyed. Cf. Rice, supra, at 230 (“[W]e start with the assumption that the historic police powers of the States” are not displaced by a federal statute “unless that was the clear and manifest purpose of Congress”); Florida Lime & Avocado Growers, Inc. v. Paul, 373 U. S. 132, 146 (1963).

While it is doubtful that any State, or indeed any reasonable person, would argue that it is wise policy to allow students to carry guns on school premises, considerable disagreement exists about how best to accomplish that goal. In this circumstance, the theory and utility of our federalism are revealed, for the States may perform their role as laboratories for experimentation to devise various solutions where the best solution is far from clear. See San Antonio Independent School Dist. v. Rodriguez, 411 U. S. 1, 49-50 (1973); New State Ice Co. v. Liebmann, 285 U. S. 262, 311 (1932) (Brandéis, J., dissenting).

If a State or municipality determines that harsh criminal sanctions are necessary and wise to deter students from carrying guns on school premises, the reserved powers of the States are sufficient to enact those measures. Indeed, over 40 States already have criminal laws outlawing the possession of firearms on or near school grounds. See, e. g., Alaska Stat. Ann. §§ 11.61.195(a)(2)(A), 11.61.220(a)(4)(A) (Supp. 1994); Cal. Penal Code Ann. § 626.9 (West Supp. 1994); Mass. Gen. Laws § 269:10(j) (1992); N. J. Stat. Ann. § 2C:39-5(e) (West Supp. 1994); Va. Code Ann. § 18.2-308.1 (1988); Wis. Stat. § 948.605 (1991-1992).

Other, more practicable means to rid the schools of guns may be thought by the citizens of some States to be preferable for the safety and welfare of the schools those States are *582charged with maintaining. See Brief for National Conference of State Legislatures et al. as Amici Curiae 26-30 (injection of federal officials into local problems causes friction and diminishes political accountability of state and local governments). These might include inducements to inform on violators where the information leads to arrests or confiscation of the guns, see Lima, Schools May Launch Weapons Hot Line, Los Angeles Times, Ventura Cty. East ed., Jan. 13, 1995, p. Bl, col. 5; Reward for Tips on Guns in Tucson Schools, The Arizona Republic, Jan. 7, 1995, p. B2; programs to encourage the voluntary surrender of guns with some provision for amnesty, see Zaidan, Akron Rallies to Save Youths, The Plain Dealer, Mar. 2, 1995, p. IB; Swift, Legislators Consider Plan to Get Guns Off Streets, Hartford Courant, Apr. 29, 1992, p. A4; penalties imposed on parents or guardians for failure to supervise the child, see, e. g., Okla. Stat., Tit. 21, § 858 (Supp. 1995) (fining parents who allow students to possess firearm at school); Tenn. Code Ann. § 39-17-1312 (Supp. 1992) (misdemeanor for parents to allow student to possess firearm at school); Straight Shooter: Gov. Casey’s Reasonable Plan to Control Assault Weapons, Pittsburgh Post-Gazette, Mar. 14,1994, p. B2 (proposed bill); Bailey, Anti-Crime Measures Top Legislators’ Agenda, Los Angeles Times, Orange Cty. ed., Mar. 7, 1994, p. Bl, col. 2 (same); Krupa, New Gun-Control Plans Could Tighten Local Law, The Boston Globe, June 20,1993, p. 29; laws providing for suspension or expulsion of gun-toting students, see, e. g., Ala. Code § 16-1-24.1 (Supp. 1994); Ind. Code § 20-8.1-5-4(b)(1)(D) (1993); Ky. Rev. Stat. Ann. § 158.150(1)(a) (Michie 1992); Wash. Rev. Code § 9.41.280 (1994), or programs for expulsion with assignment to special facilities, see Martin, Legislators Poised to Take Harsher Stand on Guns in Schools, The Seattle Times, Feb. 1, 1995, p. Bl (automatic year-long expulsion for students with guns and intense semester-long reentry program).

*583The statute now before us forecloses the States from experimenting and exercising their own judgment in an area to which States lay claim by right of history and expertise, and it does so by regulating an activity beyond the realm of commerce in the ordinary and usual sense of that term. The tendency of this statute to displace state regulation in areas of traditional state concern is evident from its territorial operation. There are over 100,000 elementary and secondary schools in the United States. See U. S. Dept. of Education, National Center for Education Statistics, Digest of Education Statistics 73, 104 (NCES 94-115, 1994) (Tables 63, 94). Each of these now has an invisible federal zone extending 1,000 feet beyond the (often irregular) boundaries of the school property. In some communities no doubt it would be difficult to navigate without infringing on those zones. Yet throughout these areas, school officials would find their own programs for the prohibition of guns in danger of displacement by the federal authority unless the State chooses to enact a parallel rule.

This is not a case where the etiquette of federalism has been violated by a formal command from the National Government directing the State to enact a certain policy, cf. New York v. United States, 505 U. S. 144 (1992), or to organize its governmental functions in a certain way, cf. FERC v. Mississippi, 456 U. S., at 781 (O’Connor, J., concurring in judgment in part and dissenting in part). While the intrusion on state sovereignty may not be as severe in this instance as in some of our recent Tenth Amendment cases, the intrusion is nonetheless significant. Absent a stronger connection or identification with commercial concerns that are central to the Commerce Clause, that interference contradicts the federal balance the Framers designed and that this Court is obliged to enforce.

For these reasons, I join in the opinion and judgment of the Court.

*584Justice Thomas,

concurring.

The Court today properly concludes that the Commerce Clause does not grant Congress the authority to prohibit gun possession within 1,000 feet of a school, as it attempted to do in the Gun-Free School Zones Act of 1990, Pub. L. 101-647, 104 Stat. 4844. Although I join the majority, I write separately to observe that our case law has drifted far from the original understanding of the Commerce Clause. In a future case, we ought to temper our Commerce Clause jurisprudence in a manner that both makes sense of our more recent case law and is more faithful to the original understanding of that Clause.

We have said that Congress may regulate not only “Commerce . . . among the several States,” U. S. Const., Art. I, § 8, cl. 3, but also anything that has a “substantial effect” on such commerce. This test, if taken to its logical extreme, would give Congress a “police power” over all aspects of American life. Unfortunately, we have never come to grips with this implication of our substantial effects formula. Although we have supposedly applied the substantial effects test for the past 60 years, we always have rejected readings of the Commerce Clause and the scope of federal power that would permit Congress to exercise a police power; our cases are quite clear that there are real limits to federal power. See New York v. United States, 505 U. S. 144, 155 (1992) (“[N]o one disputes the proposition that ‘[t]he Constitution created a Federal Government of limited powers’ ”) (quoting Gregory v. Ashcroft, 501 U. S. 452, 457 (1991); Maryland v. Wirtz, 392 U. S. 183, 196 (1968); NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1, 37 (1937). Cf. Chisholm v. Georgia, 2 Dall. 419, 435 (1793) (Iredell, J.) (“Each State in the Union is sovereign as to all the powers reserved. It must necessarily be so, because the United States have no claim to any authority but such as the States have surrendered to them”) (emphasis deleted). Indeed, on this crucial point, the majority and Justice Breyer agree in principle: The Federal *585Government has nothing approaching a police power. Compare ante, at 556-558, with post, at 624.

While the principal dissent concedes that there are limits to federal power, the sweeping nature of our current test enables the dissent to argue that Congress can regulate gun possession. But it seems to me that the power to regulate “commerce” can by no means encompass authority over mere gun possession, any more than it empowers the Federal Government to regulate marriage, littering, or cruelty to animals, throughout the 50 States. Our Constitution quite properly leaves such matters to the individual States, notwithstanding these activities’ effects on interstate commerce. Any interpretation of the Commerce Clause that even suggests that Congress could regulate such matters is in need of reexamination.

In an appropriate case, I believe that we must further reconsider our “substantial effects” test with an eye toward constructing a standard that reflects the text and history of the Commerce Clause without totally rejecting our more recent Commerce Clause jurisprudence.

Today, however, I merely support the Court’s conclusion with a discussion of the text, structure, and history of the Commerce Clause and an analysis of our early case law. My goal is simply to show how far we have departed from the original understanding and to demonstrate that the result we reach today is by no means “radical,” see post, at 602 (Stevens, J., dissenting). I also want to point out the necessity of refashioning a coherent test that does not tend to “obliterate the distinction between what is national and what is local and create a completely centralized government.” Jones & Laughlin Steel Corp., supra, at 37.

I

At the time the original Constitution was ratified, “commerce” consisted of selling, buying, and bartering, as well as transporting for these purposes. See 1 S. Johnson, A Die*586tionary of the English Language 361 (4th ed. 1773) (defining commerce as “Intercourse; exchange of one thing for another; interchange of any thing; trade; traffick”); N. Bailey, An Universal Etymological English Dictionary (26th ed. 1789) (“trade or traffic”); T. Sheridan, A Complete Dictionary of the English Language (6th ed. 1796) (“Exchange of one thing for another; trade, traffick”). This understanding finds support in the etymology of the word, which literally means “with merchandise.” See 3 Oxford English Dictionary 552 (2d ed. 1989) (com — “with”; merci — “merchandise”). In fact, when Federalists and Anti-Federalists discussed the Commerce Clause during the ratification period, they often used trade (in its selling/bartering sense) and commerce interchangeably. See The Federalist No. 4, p. 22 (J. Jay) (asserting that countries will cultivate our friendship when our “trade” is prudently regulated by Federal Government);1 id., No. 7, at 39-40 (A. Hamilton) (discussing “competitions of commerce” between States resulting from state “regulations of trade”); id., No. 40, at 262 (J. Madison) (asserting that it was an “acknowledged object of the Convention .. . that the regulation of trade should be submitted to the general government”); Lee, Letters of a Federal Farmer No. 5, in Pamphlets on the Constitution of the United States 319 (P. Ford ed. 1888); Smith, An Address to the People of the State of New-York, in id., at 107.

As one would expect, the term “commerce” was used in contradistinction to productive activities such as manufacturing and agriculture. Alexander Hamilton, for example, repeatedly treated commerce, agriculture, and manufacturing as three separate endeavors. See, e. g., The Federalist No. 36, at 224 (referring to “agriculture, commerce, manufactures”); id., No. 21, at 133 (distinguishing commerce, arts, and industry); id., No. 12, at 74 (asserting that commerce and agriculture have shared interests). The same distinctions *587were made in the state ratification conventions. See, e. g., 2 Debates in the Several State Conventions on the Adoption of the Federal Constitution 57 (J. Elliot ed. 1836) (hereinafter Debates) (T. Dawes at Massachusetts convention); id., at 336 (M. Smith at New York convention).

Moreover, interjecting a modern sense of commerce into the Constitution generates significant textual and structural problems. For example, one cannot replace “commerce” with a different type of enterprise, such as manufacturing. When a manufacturer produces a car, assembly cannot take place “with a foreign nation” or “with the Indian Tribes.” Parts may come from different States or other nations and hence may have been in the flow of commerce at one time, but manufacturing takes place at a discrete site. Agriculture and manufacturing involve the production of goods; commerce encompasses traffic in such articles.

The Port Preference Clause also suggests that the term “commerce” denoted sale and/or transport rather than business generally. According to that Clause, “[n]o Preference shall be given by any Regulation of Commerce or Revenue to the Ports of one State over those of another.” U. S. Const., Art. I, § 9, cl. 6. Although it is possible to conceive of regulations of manufacturing or farming that prefer one port over another, the more natural reading is that the Clause prohibits Congress from using its commerce power to channel commerce through certain favored ports.

The Constitution not only uses the word “commerce” in a narrower sense than our case law might suggest, it also does not support the proposition that Congress has authority over all activities that “substantially affect” interstate commerce. The Commerce Clause2 does not state that Congress may *588“regulate matters that substantially affect commerce with foreign Nations, and among the several States, and with the Indian Tribes.” In contrast, the Constitution itself temporarily prohibited amendments that would “affect” Congress’ lack of authority to prohibit or restrict the slave trade or to enact unproportioned direct taxation. Art. V. Clearly, the Framers could have drafted a Constitution that contained a “substantially affects interstate commerce” Clause had that been their objective.

In addition to its powers under the Commerce Clause,' Congress has the authority to enact such laws as are “necessary and proper” to carry into execution its power to regulate commerce among the several States. U. S. Const., Art. I, § 8, cl. 18. But on this Court’s understanding of congressional power under these two Clauses, many of Congress’ other enumerated powers under Art. I, § 8, are wholly superfluous. After all, if Congress may regulate all matters that substantially affect commerce, there is no need for the Constitution to specify that Congress may enact bankruptcy laws, cl. 4, or coin money and fix the standard of weights and measures, cl. 5, or punish counterfeiters of United States coin and securities, cl. 6. Likewise, Congress would not need the separate authority to establish post offices and post roads, cl. 7, or to grant patents and copyrights, cl. 8, or to “punish Piracies and Felonies committed on the high Seas,” cl. 10. It might not even need the power to raise and support an Army and Navy, els. 12 and 13, for fewer people would engage in commercial shipping if they thought that a foreign power could expropriate their property with ease. Indeed, if Congress could regulate matters that substantially affect interstate commerce, there would have been no need to spec*589ify that Congress can regulate international trade and commerce with the Indians. As the Framers surely understood, these other branches of trade substantially affect interstate commerce.

Put simply, much if not all of Art. I, § 8 (including portions of the Commerce Clause itself), would be surplusage if Congress had been given authority over matters that substantially affect interstate commerce. An interpretation of cl. 3 that makes the rest of § 8 superfluous simply cannot be correct. Yet this Court’s Commerce Clause jurisprudence has endorsed just such an interpretation: The power we have accorded Congress has swallowed Art. I, § 8.3

Indeed, if a “substantial effects” test can be appended to the Commerce Clause, why not to every other power of the Federal Government? There is no reason for singling out the Commerce Clause for special treatment. Accordingly, Congress could regulate all matters that “substantially affect” the Army and Navy, bankruptcies, tax collection, expenditures, and so on. In that case, the Clauses of §8 all mutually overlap, something we can assume the Founding Fathers never intended.

Our construction of the scope of congressional authority has the additional problem of coming close to turning the Tenth Amendment on its head. Our case law could be read to reserve to the United States all powers not expressly prohibited by the Constitution. Taken together, these fundamental textual problems should, at the very least, convince us that the “substantial effects” test should be reexamined.

*590II

The exchanges during the ratification campaign reveal the relatively limited reach of the Commerce Clause and of federal power generally. The Founding Fathers confirmed that most areas of life (even many matters that would have substantial effects on commerce) would remain outside the reach of the Federal Government. Such affairs would continue to be under the exclusive control of the States.

Early Americans understood that commerce, manufacturing, and agriculture, while distinct activities, were intimately related and dependent on each other — that each “substantially affected” the others. After all, items produced by farmers and manufacturers were the primary articles of commerce at the time. If commerce was more robust as a result of federal superintendence, farmers and manufacturers could benefit. Thus, Oliver Ellsworth of Connecticut attempted to convince farmers of the benefits of regulating commerce. “Your property and riches depend on a ready demand and generous price for the produce you can annually spare,” he wrote, and these conditions exist “where trade flourishes and when the merchant can freely export the produce of the country” to nations that will pay the highest price. A Landholder No. 1, Connecticut Courant, Nov. 5, 1787, in 3 Documentary History of the Ratification of the Constitution 399 (M. Jensen ed. 1978) (hereinafter Documentary History). See also The Federalist No. 35, at 219 (A. Hamilton) (“[Discerning citizens are well aware that the mechanic and manufacturing arts furnish the materials of mercantile enterprise and industry. Many of them indeed are immediately connected with the operations of commerce. They know that the merchant is their natural patron and friend”); id., at 221 (“Will not the merchant... be disposed to cultivate ... the interests of the mechanic and manufacturing arts to which his commerce is so nearly allied?”); A Jerseyman: To the Citizens of New Jersey, Trenton Mercury, Nov. 6,1787, in 3 Documentary History 147 (noting that agriculture will serve as *591a “source of commerce”); Marcus, The New Jersey Journal, Nov. 14, 1787, id., at 152 (both the mechanic and the farmer benefit from the prosperity of commerce). William Davie, a delegate to the North Carolina Convention, illustrated the close link best: “Commerce, sir, is the nurse of [agriculture and manufacturing]. The merchant furnishes the planter with such articles as he cannot manufacture himself, and finds him a market for his produce. Agriculture cannot flourish if commerce languishes; they are mutually dependent on each other.” 4 Debates 20.

Yet, despite being well aware that agriculture, manufacturing, and other matters substantially affected commerce, the founding generation did not cede authority over all these activities to Congress. Hamilton, for instance, acknowledged that the Federal Government could not regulate agriculture and like concerns:

“The administration of private justice between the citizens of the same State, the supervision of agriculture and of other concerns of a similar nature, all those things in short which are proper to be provided for by local legislation, can never be desirable cares of a general jurisdiction.” The Federalist No. 17, at 106.

In the unlikely event that the Federal Government would attempt to exercise authority over such matters, its effort “would be as troublesome as it would be nugatory.” Ibid4

*592The comments of Hamilton and others about federal power reflected the well-known truth that the new Government would have only the limited and enumerated powers found in the Constitution. See, e. g., 2 Debates 267-268 (A. Hamilton at New York Convention) (noting that there would be just cause for rejecting the Constitution if it would enable the Federal Government to “alter, or abrogate ... [a State’s] civil and criminal institutions [or] penetrate the recesses of domestic life, and control, in all respects, the private conduct of individuals”); The Federalist No. 45, at 313 (J. Madison); 3 Debates 259 (J. Madison) (Virginia Convention); R. Sherman & O. Ellsworth, Letter to Governor Huntington, Sept. 26, 1787, in 3 Documentary History 352; J. Wilson, Speech in the State House Yard, Oct. 6, 1787, in 2 id., at 167-168. Agriculture and manufacture, since they were not surrendered to the Federal Government, were state concerns. See The Federalist No. 34, at 212-213 (A. Hamilton) (observing that the “internal encouragement of agriculture and manufactures” was an object of state expenditure). Even before the passage of the Tenth Amendment, it was apparent that Congress would possess only those powers “herein granted” by the rest of the Constitution. Art. I, § 1.

. Where the Constitution was meant to grant federal authority over an activity substantially affecting interstate commerce, the Constitution contains an enumerated power over that particular activity. Indeed, the Framers knew that many of the other enumerated powers in § 8 dealt with matters that substantially affected interstate commerce. Madison, for instance, spoke of the bankruptcy power as being “intimately connected with the regulation of commerce.” The Federalist No. 42, at 287. Likewise, Hamilton urged that “[i]f we mean to be a commercial people or even to be secure on our Atlantic side, we must endeavour as soon as possible to have a navy.” Id., No. 24, at 157.

In short, the Founding Fathers were well aware of what the principal dissent calls “‘economic . . . realities.’” See *593post, at 625 (Breyer, J.) (quoting North American Co. v. SEC, 327 U. S. 686, 705 (1946)). Even though the boundary between commerce and other matters may ignore “economic reality” and thus seem arbitrary or artificial to some, we must nevertheless respect a constitutional line that does not grant Congress power over all that substantially affects interstate commerce.

Ill

If the principal dissent’s understanding of our early case law were correct, there might be some reason to doubt this view of the original understanding of the Constitution. According to that dissent, Chief Justice Marshall’s opinion in Gibbons v. Ogden, 9 Wheat. 1 (1824), established that Congress may control all local activities that “significantly affect interstate commerce,” post, at 615. And, “with the exception of one wrong turn subsequently corrected,” this has been the “traditiona[l]” method of interpreting the Commerce Clause. Post, at 631 (citing Gibbons and United States v. Darby, 312 U. S. 100, 116-117 (1941)).

In my view, the dissent is wrong about the holding and reasoning of Gibbons. Because this error leads the dissent to characterize the first 150 years of this Court’s case law as a “wrong turn,” I feel compelled to put the last 50 years in proper perspective.

A

In Gibbons, the Court examined whether a federal law that licensed ships to engage in the “coasting trade” preempted a New York law granting a 30-year monopoly to Robert Livingston and Robert Fulton to navigate the State’s waterways by steamship. In concluding that it did, the Court noted that Congress could regulate “navigation” because “[a]ll America ... has uniformly understood, the word ‘commerce,’ to comprehend navigation. It was so understood, and must have been so understood, when the constitution was framed.” 9 Wheat., at 190. The Court also ob*594served that federal power over commerce “among the several States” meant that Congress could regulate commerce conducted partly within a State. Because a portion of interstate commerce and foreign commerce would almost always take place within one or more States, federal power over interstate and foreign commerce necessarily would extend into the States. Id., at 194-196.

At the same time, the Court took great pains to make clear that Congress could not regulate commerce “which is completely internal, which is carried on between man and man in a State, or between different parts of the same State, and which does not extend to or affect other States.” Id., at 194. Moreover, while suggesting that the Constitution might not permit States to regulate interstate or foreign commerce, the Court observed that “[inspection laws, quarantine laws, health laws of every description, as well as laws for regulating the internal commerce of a State” were but a small part “of that immense mass of legislation . . . not surrendered to a general government.” Id., at 203. From an early moment, the Court rejected the notion that Congress can regulate everything that affects interstate commerce. That the internal commerce of the States and the numerous state inspection, quarantine, and health laws had substantial effects on interstate commerce cannot be doubted. Nevertheless, they were not “surrendered to the general government.”

Of course, the principal dissent is not the first to misconstrue Gibbons. For instance, the Court has stated that Gibbons “described the federal commerce power with a breadth never yet exceeded.” Wickard v. Filburn, 317 U. S. 111, 120 (1942). See also Perez v. United States, 402 U. S. 146, 151 (1971) (claiming that with Darby and Wickard, “the broader view of the Commerce Clause announced by Chief Justice Marshall had been restored”). I believe that this misreading stems from two statements in Gibbons.

First, the Court made the uncontroversial claim that federal power does not encompass “commerce” that “does *595not extend to or affect other States.” 9 Wheat., at 194 (emphasis added). From this statement, the principal dissent infers that whenever an activity affects interstate commerce, it necessarily follows that Congress can regulate such activities. Of course, Chief Justice Marshall said no such thing and the inference the dissent makes cannot be drawn.

There is a much better interpretation of the “affect[s]” language: Because the Court had earlier noted that the commerce power did not extend to wholly intrastate commerce, the Court was acknowledging that although the line between intrastate and interstate/foreign commerce would be difficult to draw, federal authority could not be construed to cover purely intrastate commerce. Commerce that did not affect another State could never be said to be commerce “among the several States.”

But even if one were to adopt the dissent’s reading, the “affect[s]” language, at most, permits Congress to regulate only intrastate commerce that substantially affects interstate and foreign commerce. There is no reason to believe that Chief Justice Marshall was asserting that Congress could regulate all activities that affect interstate commerce. See ibid.

The second source of confusion stems from the Court’s praise for the Constitution’s division of power between the States and the Federal Government:

“The genius and character of the whole government seem to be, that its action is to be applied to all the external concerns of the nation, and to those internal concerns which affect the States generally; but not to those which are completely within a particular State, which do not affect other States, and with which it is not necessary to interfere, for the purpose of executing some of the general powers of the government.” Id., at 195.

*596In this passage, the Court merely was making the well understood point that the Constitution commits matters of “national” concern to Congress and leaves “local” matters to the States. The Court was not saying that whatever Congress believes is a national matter becomes an object of federal control. The matters of national concern are enumerated in the Constitution: war, taxes, patents, and copyrights, uniform rules of naturalization and bankruptcy, types of commerce, and so on. See generally Art. I, § 8. Gibbons’ emphatic statements that Congress could not regulate many matters that affect commerce confirm that the Court did not read the Commerce Clause as granting Congress control over matters that “affect the States generally.”5 Gibbons simply cannot be construed as the principal dissent would have it.

B

I am aware of no cases prior to the New Deal that characterized the power flowing from the Commerce Clause as sweepingly as does our substantial effects test. My review of the case law indicates that the substantial effects test is but an innovation of the 20th century.

Even before Gibbons, Chief Justice Marshall, writing for the Court in Cohens v. Virginia, 6 Wheat. 264 (1821), noted that Congress had “no general right to punish murder committed within any of the States,” id., at 426, and that it was “clear that congress cannot punish felonies generally,” id., at 428. The Court’s only qualification was that Congress could enact such laws for places where it enjoyed plenary powers — for instance, over the District of Columbia. Id., at 426. Thus, whatever effect ordinary murders, or robbery, or gun possession might have on interstate commerce (or on any *597other subject of federal concern) was irrelevant to the question of congressional power.6

United States v. Dewitt, 9 Wall. 41 (1870), marked the first time the Court struck down a federal law as exceeding the power conveyed by the Commerce Clause. In a two-page opinion, the Court invalidated a nationwide law prohibiting all sales of naphtha and illuminating oils. In so doing, the Court remarked that the Commerce Clause “has always been understood as limited by its terms; and as a virtual denial of any power to interfere with the internal trade and business of the separate States.” Id., at 44. The law in question was “plainly a regulation of police,” which could have constitutional application-only where Congress had exclusive authority, such as the territories. Id., at 44-45. See also License Tax Cases, 5 Wall. 462, 470-471 (1867) (Congress cannot interfere with the internal commerce and business of a State); Trade-Mark Cases, 100 U. S. 82 (1879) (Congress *598cannot regulate internal commerce and thus may not establish national trademark registration).

In United States v. E. C. Knight Co., 156 U. S. 1 (1895), this Court held that mere attempts to monopolize the manufacture of sugar could not be regulated pursuant to the Commerce Clause. Raising echoes of the discussions of the Framers regarding the intimate relationship between commerce and manufacturing, the Court declared that “Commerce succeeds to manufacture, and is not a part of it.” Id., at 12. The Court also approvingly quoted from Kidd v. Pearson, 128 U. S. 1, 20 (1888):

‘“No distinction is more popular to the common mind, or more clearly expressed in economic and political literature, than that between manufacture and commerce .... If it be held that the term [commerce] includes the regulation of all such manufactures as are intended to be the subject of commercial transactions in the future, it is impossible to deny that it would also include all productive industries that contemplate the same thing. The result would be that Congress would be invested ... with the power to regulate, not only manufactures, but also agriculture, horticulture, stock raising, domestic fisheries, mining — in short, every branch of human industry.’” E. C. Knight, supra, at 14.,

If federal power extended to these types of production “comparatively little of business operations and affairs would be left for state control.” Id., at 16. See also Newberry v. United States, 256 U. S. 232, 257 (1921) (“It is settled ... that the power to regulate interstate and foreign commerce does not reach whatever is essential thereto. Without agriculture, manufacturing, mining, etc., commerce could not exist, but this fact does not suffice to subject them to the control of Congress”). Whether or not manufacturing, agriculture, or other matters substantially affected interstate commerce was irrelevant.

*599As recently as 1936, the Court continued to insist that the Commerce Clause did not reach the wholly internal business of the States. See Carter v. Carter Coal Co., 298 U. S. 238, 308 (1936) (Congress may not regulate mine labor because “[t]he relation of employer and employee is a local relation”); see also A. L. A. Schechter Poultry Corp. v. United States, 295 U. S. 495, 543-550 (1935) (holding that Congress may not regulate intrastate sales of sick chickens or the labor of employees involved in intrastate poultry sales). The Federal Government simply could not reach such subjects regardless of their effects on interstate commerce.

These cases all establish a simple point: From the time of the ratification of the Constitution to the mid-1930’s, it was widely understood that the Constitution granted Congress only limited powers, notwithstanding the Commerce Clause.7 Moreover, there was no question that activities wholly separated from business, such as gun possession, were beyond the reach of the commerce power. If anything, the “wrong turn” was the Court’s dramatic departure in the 1930’s from a century and a half of precedent.

IV

Apart from its recent vintage and its corresponding lack of any grounding in the original understanding of the Constitution, the substantial effects test suffers from the further *600flaw that it appears to grant Congress a police power over the Nation. When asked at oral argument if there were any limits to the Commerce Clause, the Government was at a loss for words. Tr. of Oral Arg. 5. Likewise, the principal dissent insists that there are limits, but it cannot muster even one example. Post, at 624. Indeed, the dissent implicitly concedes that its reading has no limits when it criticizes the Court for “threatening] legal uncertainty in an area of law that. . . seemed reasonably well settled.” Post, at 630. The one advantage of the dissent’s standard is certainty: It is certain that under its analysis everything may be regulated under the guise of the Commerce Clause.

The substantial effects test suffers from this flaw, in part, because of its “aggregation principle.” Under so-called “class of activities” statutes, Congress can regulate whole categories of activities that are not themselves either “interstate” or “commerce.” In applying the effects test, we ask whether the class of activities as a whole substantially affects interstate commerce, not whether any specific activity within the class has such effects when considered in isolation. See Maryland v. Wirtz, 392 U. S., at 192-193 (if class of activities is “ ‘within the reach of federal power,’ ” courts may not excise individual applications as trivial) (quoting Darby, 312 U. S., at 120-121).

The aggregation principle is clever, but has no stopping point. Suppose all would agree that gun possession within 1,000 feet of a school does not substantially affect commerce, but that possession of weapons generally (knives, brass knuckles, nunchakus, etc.) does. Under our substantial effects doctrine, even though Congress cannot single out gun possession, it can prohibit weapon possession generally. But one always can draw the circle broadly enough to cover an activity that, when taken in isolation, would not have substantial effects on commerce. Under our jurisprudence, if Congress passed an omnibus “substantially affects interstate commerce” statute, purporting to regulate every aspect of human existence, the Act apparently would be constitutional. *601Even though particular sections may govern only trivial activities, the statute in the aggregate regulates matters that substantially affect commerce.

V

This extended discussion of the original understanding and our first century and a half of case law does not necessarily require a wholesale abandonment of our more recent opinions.8 It simply reveals that our substantial effects test is far removed from both the Constitution and from our early case law and that the Court’s opinion should not be viewed as “radical” or another “wrong turn” that must be corrected in the future.9 The analysis also suggests that we ought to temper our Commerce Clause jurisprudence.

*602Unless the dissenting Justices are willing to repudiate our long-held understanding of the limited nature of federal power, I would think that they, too, must be willing to reconsider the substantial effects test in a future case. If we wish to be true to a Constitution that does not cede a police power to the Federal Government, our Commerce Clause’s boundaries simply cannot be “defined” as being “ ‘commensurate with the national needs’ ” or self-consciously intended to let the Federal Government “‘defend itself against economic forces that Congress decrees inimical or destructive of the national economy.’ ” See post, at 625 (Breyer, J., dissenting) (quoting North American Co. v. SEC, 327 U. S., at 705). Such a formulation of federal power is no test at all: It is a blank check.

At an appropriate juncture, I think we must modify our Commerce Clause jurisprudence. Today, it is easy enough to say that the Clause certainly does not empower Congress to ban gun possession within 1,000 feet of a school.

Justice Stevens,

dissenting.

The welfare of our future “Commerce with foreign Nations, and among the several States,” U. S. Const., Art. I, § 8, cl. 3, is vitally dependent on the character of the education of our children. I therefore agree entirely with Justice Breyer’s explanation of why Congress has ample power to prohibit the possession of firearms in or near schools — just as it may protect the school environment from harms posed by controlled substances such as asbestos or alcohol. I also agree with Justice Souter’s exposition of the radical character of the Court’s holding and its kinship with the discredited, pre-Depression version of substantive due process. Cf. Dolan v. City of Tigard, 512 U. S. 374, 4 05-411 (1994) (Stevens, J., dissenting). I believe, however, that the Court’s extraordinary decision merits this additional comment.

Guns are both articles of commerce and articles that can be used to restrain commerce. Their possession is the con*603sequence, either directly or indirectly, of commercial activity. In my judgment, Congress’ power to regulate commerce in firearms includes the power to prohibit possession of guns at any location because of their potentially harmful use; it necessarily follows that Congress may also prohibit their possession in particular markets. The market for the possession of handguns by school-age children is, distressingly, substantial.* Whether or not the national interest in eliminating that market would have justified federal legislation in 1789, it surely does today.

Justice Souter,

dissenting.

In reviewing congressional legislation under the Commerce Clause, we defer to what is often a merely implicit congressional judgment that its regulation addresses a subject substantially affecting interstate commerce “if there is any rational basis for such a finding.” Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S. 264, 276 (1981); Preseault v. ICC, 494 U. S. 1, 17 (1990); see Maryland v. Wirtz, 392 U. S. 183, 190 (1968), quoting Katzenbach v. McClung, 379 U. S. 294, 303-304 (1964). If that congressional determination is within the realm of reason, “the only remaining question for judicial inquiry is whether ‘the means chosen by Congress [are] reasonably adapted to the end permitted by the Constitution.’” Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., supra, at 276, quoting Heart of Atlanta Motel, Inc. v. United States, 379 U. S. 241, 262 (1964); see also Preseault v. ICC, supra, at 17.1

*604The practice of deferring to rationally based legislative judgments “is a paradigm of judicial restraint.” FCC v. Beach Communications, Inc., 508 U. S. 307, 314 (1993). In judicial review under the Commerce Clause, it reflects our respect for the institutional competence of the Congress on a subject expressly assigned to it by the Constitution and our appreciation of the legitimacy that comes from Congress’s political accountability in dealing with matters open to a wide range of possible choices. See id., at 313-316; Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., supra, at 276; United States v. Carotene Products Co., 304 U. S. 144, 147, 151-154 (1938); cf. Williamson v. Lee Optical of Okla., Inc., 348 U. S. 483, 488 (1955).

It was not ever thus, however, as even a brief overview of Commerce Clause history during the past century reminds us. The modern respect for the competence and primacy of Congress in matters affecting commerce developed only after one of this Court’s most chastening experiences, when it perforce repudiated an earlier and untenably expansive conception of judicial review in derogation of congressional commerce power. A look at history’s sequence will serve to show how today’s decision tugs the Court off course, leading it to suggest opportunities for further developments that would be at odds with the rule of restraint to which the Court still wisely states adherence.

I

Notwithstanding the Court’s recognition of a broad commerce power in Gibbons v. Ogden, 9 Wheat. 1, 196-197 (1824) (Marshall, C. J.), Congress saw few occasions to exercise that power prior to Reconstruction, see generally 2 C. Warren, The Supreme Court in United States History 729-739 (rev. ed. 1935), and it was really the passage of the Interstate Commerce Act of 1887 that opened a new age of congressional reliance on the Commerce Clause for authority to exercise general police powers at the national level, see id., at *605729-730. Although the Court upheld a fair amount of the ensuing legislation as being within the commerce power, see, e. g., Stafford v. Wallace, 258 U. S. 495 (1922) (upholding an Act regulating trade practices in the meat packing industry); Shreveport Rate Cases, 234 U. S. 342 (1914) (upholding Interstate Commerce Commission order to equalize interstate and intrastate rail rates); see generally Warren, supra, at 729-739, the period from the turn of the century to 1937 is better noted for a series of cases applying highly formalistic notions of “commerce” to invalidate federal social and economic legislation, see, e. g., Carter v. Carter Coal Co., 298 U. S. 238, 303-304 (1936) (striking Act prohibiting unfair labor practices in coal industry as regulation of “mining” and “production,” not “commerce”); A. L. A. Schechter Poultry Corp. v. United States, 295 U. S. 495, 545-548 (1935) (striking congressional regulation of activities affecting interstate commerce only “indirectly”); Hammer v. Dagenhart, 247 U. S. 251 (1918) (striking Act prohibiting shipment in interstate commerce of goods manufactured at factories using child labor because the Act regulated “manufacturing,” not “commerce”); Adair v. United States, 208 U. S. 161 (1908) (striking protection of labor union membership as outside “commerce”).

These restrictive views of commerce subject to congressional power complemented the Court’s activism in limiting the enforceable scope of state economic regulation. It is most familiar history that during this same period the Court routinely invalidated state social and economic legislation under an expansive conception of Fourteenth Amendment substantive due process. See, e. g., Louis K. Liggett Co. v. Baldridge, 278 U. S. 105 (1928) (striking state law requiring pharmacy owners to be licensed as pharmacists); Coppage v. Kansas, 236 U. S. 1 (1915) (striking state law prohibiting employers from requiring their employees to agree not to join labor organizations); Lochner v. New York, 198 U. S. 45 (1905) (striking state law establishing maximum working hours for bakers). See generally L. Tribe, American Consti*606tutional Law 568-574 (2d ed. 1988). The fulcrums of judicial review in these cases were the notions of liberty and property characteristic of laissez-faire economics, whereas the Commerce Clause cases turned on what was ostensibly a structural limit of federal power, but under each conception of judicial review the Court’s character for the first third of the century showed itself in exacting judicial scrutiny of a legislature’s choice of economic ends and of the legislative means selected to reach them.

It was not merely coincidental, then, that sea changes in the Court’s conceptions of its authority under the Due Process and Commerce Clauses occurred virtually together, in 1937, with West Coast Hotel Co. v. Parrish, 300 U. S. 379, and NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1. See Stern, The Commerce Clause and the National Economy, 1933-1946, 59 Harv. L. Rev. 645, 674-682 (1946). In West Coast Hotel, the Court’s rejection of a due process challenge to a state law fixing minimum wages for women and children marked the abandonment of its expansive protection of contractual freedom. Two weeks later, Jones & Laughlin affirmed congressional commerce power to authorize NLRB injunctions against unfair labor practices. The Court’s finding that the regulated activity had a direct enough effect on commerce has since been seen as beginning the abandonment, for practical purposes, of the formalistic distinction between direct and indirect effects.

In the years following these decisions, deference to legislative policy judgments on commercial regulation became the powerful theme under both the Due Process and Commerce Clauses, see United States v. Carolene Products Co., 304 U. S., at 147-148, 152; United States v. Darby, 312 U. S. 100, 119-121 (1941); United States v. Wrightwood Dairy Co., 315 U. S. 110, 118-119 (1942), and in due course that deference became articulate in the standard of rationality review. In due process litigation, the Court’s statement of a rational *607basis test came quickly. See United States v. Carolene Products Co., supra, at 152; see also Williamson v. Lee Optical Co., supra, at 489-490. The parallel formulation of the Commerce Clause test came later, only because complete elimination of the direct/indirect effects dichotomy and acceptance of the cumulative effects doctrine, Wickard v. Filburn, 317 U. S. 111, 125, 127-129 (1942); United States v. Wrightwood Dairy Co., supra, at 124-126, so far settled the pressing issues of congressional power over commerce as to leave the Court for years without any need to phrase a test explicitly deferring to rational legislative judgments. The moment came, however, with the challenge to congressional Commerce Clause authority to prohibit racial discrimination in places of public accommodation, when the Court simply made explicit what the earlier cases had implied: “where we find that the legislators, in light of the facts and testimony before them, have a rational basis for finding a chosen regulatory scheme necessary to the protection of commerce, our investigation is at an end.” Katzenbach v. McClung, 379 U. S., at 303-304, discussing United States v. Darby, supra; see Heart of Atlanta Motel, Inc. v. United States, 379 U. S., at 258-259. Thus, under commerce, as under due process, adoption of rational basis review expressed the recognition that the Court had no sustainable basis for subjecting economic regulation as such to judicial policy judgments, and for the past half century the Court has no more turned back in the direction of formalistic Commerce Clause review (as in deciding whether regulation of commerce was sufficiently direct) than it has inclined toward reasserting the substantive authority of Lochner due process (as in the inflated protection of contractual autonomy). See, e. g., Maryland v. Wirtz, 392 U. S., at 190, 198; Perez v. United States, 402 U. S. 146, 151-157 (1971); Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S., at 276, 277.

*608II

There is today, however, a backward glance at both the old pitfalls, as the Court treats deference under the rationality rule as subject to gradation according to the commercial or noncommercial nature of the immediate subject of the challenged regulation. See ante, at 558-561. The distinction between what is patently commercial and what is not looks much like the old distinction between what directly affects commerce and what touches it only indirectly. And the act of calibrating the level of deference by drawing a line between what is patently commercial and what is less purely so will probably resemble the process of deciding how much interference with contractual freedom was fatal. Thus, it seems fair to ask whether the step taken by the Court today does anything but portend a return to the untenable jurisprudence from which the Court extricated itself almost 60 years ago. The answer is not reassuring. To be sure, the occasion for today’s decision reflects the century’s end, not its beginning. But if it seems anomalous that the Congress of the United States has taken to regulating school yards, the Act in question is still probably no more remarkable than state regulation of bake shops 90 years ago. In any event, there is no reason to hope that the Court’s qualification of rational basis review will be any more successful than the efforts at substantive economic review made by our predecessors as the century began. Taking the Court’s opinion on its own terms, Justice Breyer has explained both the hopeless porosity of “commercial” character as a ground of Commerce Clause distinction in America’s highly connected economy, and the inconsistency of this categorization with our rational basis precedents from the last 50 years.

Further glosses on rationality review, moreover, may be in the offing. Although this case turns on commercial character, the Court gestures toward two other considerations that it might sometime entertain in applying rational basis *609scrutiny (apart from a statutory obligation to supply independent proof of a jurisdictional element): does the congressional statute deal with subjects of traditional state regulation, and does the statute contain explicit factual findings supporting the otherwise implicit determination that the regulated activity substantially affects interstate commerce? Once again, any appeal these considerations may have depends on ignoring the painful lesson learned in 1937, for neither of the Court’s suggestions would square with rational basis scrutiny.

A

The Court observes that the Gun-Free School Zones Act operates in two areas traditionally subject to legislation by the States, education and enforcement of criminal law. The suggestion is either that a connection between commerce and these subjects is remote, or that the commerce power is simply weaker when it touches subjects on which the States have historically been the primary legislators. Neither suggestion is tenable. As for remoteness, it may or may not be wise for the National Government to deal with education, but Justice Breyer has surely demonstrated that the commercial prospects of an illiterate State or Nation are not rosy, and no argument should be needed to show that hijacking interstate shipments of cigarettes can affect commerce substantially, even though the States have traditionally prosecuted robbery. And as for the notion that the commerce power diminishes the closer it gets to customary state concerns, that idea has been flatly rejected, and not long ago. The commerce power, we have often observed, is plenary. Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., supra, at 276; United States v. Darby, 312 U. S., at 114; see Garcia v. San Antonio Metropolitan Transit Authority, 469 U. S. 528, 549-550 (1985); Gibbons v. Ogden, 9 Wheat., at 196-197. Justice Harlan put it this way in speaking for the Court in Maryland v. Wirtz:

*610“There is no general doctrine implied in the Federal Constitution that the two governments, national and state, are each to exercise its powers so as not to interfere with the free and full exercise of the powers of the other. . . . [I]t is clear that the Federal Government, when acting within a delegated power, may override countervailing state interests .... As long ago as [1925], the Court put to rest the contention that state concerns might constitutionally ‘outweigh’ the importance of an otherwise valid federal statute regulating commerce.” 392 U. S., at 195-196 (citations and internal quotation marks omitted).

See also United States v. Darby, supra, at 114; Gregory v. Ashcroft, 501 U. S. 452, 460 (1991); United States v. Carolene Products Co., 304 U. S., at 147.

Nor is there any contrary authority in the reasoning of our cases imposing clear statement rules in some instances of legislation that would significantly alter the state-national balance. In the absence of a clear statement of congressional design, for example, we have refused to interpret ambiguous federal statutes to limit fundamental state legislative prerogatives, Gregory v. Ashcroft, supra, at 460-464, our understanding being that such prerogatives, through which “a State defines itself as a sovereign,” are “powers with which Congress does not readily interfere,” 501 U. S., at 460, 461. Likewise, when faced with two plausible interpretations of a federal criminal statute, we generally will take the alternative that does not force us to impute an intention to Congress to use its full commerce power to regulate conduct traditionally and ably regulated by the States. See United States v. Enmons, 410 U. S. 396, 411-412 (1973); United States v. Bass, 404 U. S. 336, 349-350 (1971); Rewis v. United States, 401 U. S. 808, 812 (1971).

These clear statement rules, however, are merely rules of statutory interpretation, to be relied upon only when the *611terms of a statute allow, United States v. Culbert, 435 U. S. 371, 379-380 (1978); see Gregory v. Ashcroft, supra, at 470; United States v. Bass, supra, at 346-347, and in cases implicating Congress’s historical reluctance to trench on state legislative prerogatives or to enter into spheres already occupied by the States, Gregory v. Ashcroft, supra, at 461; United States v. Bass, supra, at 349; see Rewis v. United States, supra, at 811-812. They are rules for determining intent when legislation leaves intent subject to question. But our hesitance to presume that Congress has acted to alter the state-federal status quo (when presented with a plausible alternative) has no relevance whatever to the enquiry whether it has the commerce power to do so or to the standard of judicial review when Congress has definitely meant to exercise that power. Indeed, to allow our hesitance to affect the standard of review would inevitably degenerate into the sort of substantive policy review that the Court found indefensible 60 years ago. The Court does not assert (and could not plausibly maintain) that the commerce power is wholly devoid of congressional authority to speak on any subject of traditional state concern; but if congressional action is not forbidden absolutely when it touches such a subject, it will stand or fall depending on the Court’s view of the strength of the legislation’s commercial justification. And here once again history raises its objections that the Court’s previous essays in overriding congressional policy choices under the Commerce Clause were ultimately seen to suffer two fatal weaknesses: when dealing with Acts of Congress (as distinct from state legislation subject to review under the theory of dormant commerce power) nothing in the Clause compelled the judicial activism, and nothing about the judiciary as an institution made it a superior source of policy on the subject Congress dealt with. There is no reason to expect the lesson would be different another time.

*612B

There remain questions about legislative findings. The Court of Appeals expressed the view, 2 F. 8d 1342, 1363-1368 (CA5 1993), that the result in this case might well have been different if Congress had made explicit findings that guns in schools have a substantial effect on interstate commerce, and the Court today does not repudiate that position, see ante, at 562-563. Might a court aided by such findings have subjected this legislation to less exacting scrutiny (or, put another way, should a court have deferred to such findings if Congress had made them)?2 The answer to either question must be no, although as a general matter findings are important and to be hoped for in the difficult cases.

It is only natural to look for help with a hard job, and reviewing a claim that Congress has exceeded the commerce power is much harder in some cases than in others. A challenge to congressional regulation of interstate garbage hauling would be easy to resolve; review of congressional regulation of gun possession in school yards is more difficult, both because the link to interstate commerce is less obvious and because of our initial ignorance of the relevant facts. In a *613case comparable to this one, we may have to dig hard to make a responsible judgment about what Congress could reasonably find, because the case may be close, and because judges tend not to be familiar with the facts that may or may not make it close. But while the ease of review may vary from case to case, it does not follow that the standard of review should vary, much less that explicit findings of fact would even directly address the standard.

The question for the courts, as all agree, is not whether as a predicate to legislation Congress in fact found that a particular activity substantially affects interstate commerce. The legislation implies such a finding, and there is no reason to entertain claims that Congress acted ultra vires intentionally. Nor is the question whether Congress was correct in so finding. The only question is whether the legislative judgment is within the realm of reason. See Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S., at 276-277; Katzenbach v. McClung, 379 U. S., at 303-304; Railroad Retirement Bd. v. Alton R. Co., 295 U. S. 330, 391-392 (1935) (Hughes, C. J., dissenting); cf. FCC v. Beach Communications, Inc., 508 U. S., at 315 (in the equal protection context, “those attacking the rationality of the legislative classification have the burden to negate every conceivable basis which might support it[;] ... it is entirely irrelevant for constitutional purposes whether the conceived reason for the challenged distinction actually motivated the legislature”) (citations and internal quotation marks omitted); Ferguson v. Skrupa, 372 U. S. 726, 731-733 (1963); Williamson v. Lee Optical Co., 348 U. S., at 487. Congressional findings do not, however, directly address the question of reasonableness; they tell us what Congress actually has found, not what it could rationally find. If, indeed, the Court were to make the existence of explicit congressional findings dispositive in some close or difficult cases something other than rationality review would be afoot. The resulting congressional obligation to justify its policy choices on the merits would imply *614either a judicial authority to review the justification (and, hence, the wisdom) of those choices, or authority to require Congress to act with some high degree of deliberateness, of which express findings would be evidence. But review for congressional wisdom would just be the old judicial pretension discredited and abandoned in 1987, and review for deliberateness would be as patently unconstitutional as an Act of Congress mandating long opinions from this Court. Such a legislative process requirement would function merely as an excuse for covert review of the merits of legislation under standards never expressed and more or less arbitrarily applied. Under such a regime, in any case, the rationality standard of review would be a thing of the past.

On the other hand, to say that courts applying the rationality standard may not defer to findings is not, of course, to say that findings are pointless. They may, in fact, have great value in telling courts what to look for, in establishing at least one frame of reference for review, and in citing to factual authority. The research underlying Justice Breyer’s dissent was necessarily a major undertaking; help is welcome, and it not incidentally shrinks the risk that judicial research will miss material scattered across the public domain or buried under pounds of legislative record. Congressional findings on a more particular plane than this record illustrates would accordingly have earned judicial thanks. But thanks do not carry the day as long as rational possibility is the touchstone, and I would not allow for the possibility, as the Court’s opinion may, ante, at 563, that the addition of congressional findings could in principle have affected the fate of the statute here.

Ill

Because Justice Breyer’s opinion demonstrates beyond any doubt that the Act in question passes the rationality review that the Court continues to espouse, today’s decision may be seen as only a misstep, its reasoning and its sugges*615tions not quite in gear with the prevailing standard, but hardly an epochal case. I would not argue otherwise, but I would raise a caveat. Not every epochal case has come in epochal trappings. Jones & Laughlin did not reject the direct-indirect standard in so many words; it just said the relation of the regulated subject matter to commerce was direct enough. 301 U. S., at 41-43. But we know what happened.

I respectfully dissent.

Justice Breyer,

with whom Justice Stevens, Justice Souter, and Justice Ginsburg join,

dissenting.

The issue in this case is whether the Commerce Clause authorizes Congress to enact a statute that makes it a crime to possess a gun in, or near, a school. 18 U. S. C. § 922(q)(1)(A) (1988 ed., Supp. V). In my view, the statute falls well within the scope of the commerce power as this Court has understood that power over the last half century.

I

In reaching this conclusion, I apply three basic principles of Commerce Clause interpretation. First, the power to “regulate Commerce . . . among the several States,” U. S. Const., Art. I, § 8, cl. 3, encompasses the power to regulate local activities insofar as they significantly affect interstate commerce. See, e. g., Gibbons v. Ogden, 9 Wheat. 1, 194-195 (1824) (Marshall, C. J.); Wickard v. Filburn, 317 U. S. 111, 125 (1942). As the majority points out, ante, at 559, the Court, in describing how much of an effect the Clause requires, sometimes has used the word “substantial” and sometimes has not. Compare, e. g., Wickard, supra, at 125 (“substantial economic effect”), with Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S. 264, 276 (1981) (“affects interstate commerce”); see also Maryland v. Wirtz, 392 U. S. 183, 196, n. 27 (1968) (cumulative effect must not be “trivial”); NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1, 37 (1937) *616(speaking of “close and substantial relation” between activity and commerce, not of “substantial effect”) (emphasis added); Gibbons, supra, at 194 (words of Commerce Clause do not “comprehend ... commerce, which is completely internal .. . and which does not. . . affect other States”). And, as the majority also recognizes in quoting Justice Cardozo, the question of degree (how much effect) requires an estimate of the “size” of the effect that no verbal formulation can capture with precision. See ante, at 567. I use the word “significant” because the word “substantial” implies a somewhat narrower power than recent precedent suggests. See, e. g., Perez v. United States, 402 U. S. 146, 154 (1971); Daniel v. Paul, 395 U. S. 298, 308 (1969). But to speak of “substantial effect” rather than “significant effect” would make no difference in this case.

Second, in determining whether a local activity will likely have a significant effect upon interstate commerce, a court must consider, not the effect of an individual act (a single instance of gun possession), but rather the cumulative effect of all similar instances (i. e., the effect of all guns possessed in or near schools). See, e. g., Wickard, supra, at 127-128. As this Court put the matter almost 50 years ago:

“[I]t is enough that the individual activity when multiplied into a general practice ... contains a threat to the interstate economy that requires preventative regulation.” Mandeville Island Farms, Inc. v. American Crystal Sugar Co., 334 U. S. 219, 236 (1948) (citations omitted).

Third, the Constitution requires us to judge the connection between a regulated activity and interstate commerce, not directly, but at one remove. Courts must give Congress a degree of leeway in determining the existence of a significant factual connection between the regulated activity and interstate commerce — both because the Constitution delegates the commerce power directly to Congress and because the *617determination requires an empirical judgment of a kind that a legislature is more likely than a court to make with accuracy. The traditional words “rational basis” capture this leeway. See Hodel, supra, at 276-277. Thus, the specific question before us, as the Court recognizes, is not whether the “regulated activity sufficiently affected interstate commerce,” but, rather, whether Congress could have had “a rational basis” for so concluding. Ante, at 557 (emphasis added).

I recognize that we must judge this matter independently. “[SJimply because Congress may conclude that a particular activity substantially affects interstate commerce does not necessarily make it so.” Hodel, supra, at 311 (Rehnquist, J., concurring in judgment). And, I also recognize that Congress did not write specific “interstate commerce” findings into the law under which Lopez was convicted. Nonetheless, as I have already noted, the matter that we review independently (i. e., whether there is a “rational basis”) already has considerable leeway built into it. And, the absence of findings, at most, deprives a statute of the benefit of some extra leeway. This extra deference, in principle, might change the result in a close case, though, in practice, it has not made a critical legal difference. See, e. g., Katzenbach v. McClung, 379 U. S. 294, 299 (1964) (noting that “no formal findings were made, which of course are not necessary”); Perez, supra, at 156-157; cf. Turner Broadcasting System, Inc. v. FCC, 512 U. S. 622, 666 (1994) (opinion of Kennedy, J.) (“Congress is not obligated, when enacting its statutes, to make a record of the type that an administrative agency or court does to accommodate judicial review”); Fullilove v. Klutznick, 448 U. S. 448, 503 (1980) (Powell, J., concurring) (“After Congress has legislated repeatedly in an area of national concern, its Members gain experience that may reduce the need for fresh hearings or prolonged debate . . .”). It would seem particularly unfortunate to make the validity of *618the statute at hand turn on the presence or absence of findings. Because Congress did make findings (though not until after Lopez was prosecuted), doing so would appear to elevate form over substance. See Pub. L. 103-322, §§ 320904 (2)(F), (G), 108 Stat. 2125, 18 U. S. C. §§ 922(q)(1)(F), (G).

In addition, despite the Court of Appeals’ suggestion to the contrary, see 2 F. 3d 1342, 1365 (CA5 1993), there is no special need here for a clear indication of Congress’ rationale. The statute does not interfere with the exercise of state or local authority. Cf., e. g., Dellmuth v. Muth, 491 U. S. 223, 227-228 (1989) (requiring clear statement for abrogation of Eleventh Amendment immunity). Moreover, any clear statement rule would apply only to determine Congress’ intended result, not to clarify the source of its authority or measure the level of consideration that went into its decision, and here there is no doubt as to which activities Congress intended to regulate. See ibid.; id., at 233 (Scalia, J., concurring) (to subject States to suits for money damages, Congress need only make that intent clear, and need not refer explicitly to the Eleventh Amendment); EEOC v. Wyoming, 460 U. S. 226, 243, n. 18 (1983) (Congress need not recite the constitutional provision that authorizes its action).

II

Applying these principles to the case at hand, we must ask whether Congress could have had a rational basis for finding a significant (or substantial) connection between gun-related school violence and interstate commerce. Or, to put the question in the language of the explicit finding that Congress made when it amended this law in 1994: Could Congress rationally have found that “violent crime in school zones,” through its effect on the “quality of education,” significantly (or substantially) affects “interstate” or “foreign commerce”? 18 U. S. C. §§ 922(q)(1)(F), (G). As long as one views the commerce connection, not as a “technical legal conception,” but as “a practical one,” Swift & Co. v. United States, 196 *619U. S. 375, 398 (1905) (Holmes, J.), the answer to this question must be yes. Numerous reports and studies — generated both inside and outside government — make clear that Congress could reasonably have found the empirical connection that its law, implicitly or explicitly, asserts. (See Appendix, infra, at 631, for a sample of the documentation, as well as for complete citations to the sources referenced below.)

For one thing, reports, hearings, and other readily available literature make clear that the problem of guns in and around schools is widespread and extremely serious. These materials report, for example, that four percent of American high school students (and six percent of inner-city high school students) carry a gun to school at least occasionally, Centers for Disease Control 2342; Sheley, McGee, & Wright 679; that 12 percent of urban high school students have had guns fired at them, ibid.; that 20 percent of those students have been threatened with guns, ibid.; and that, in any 6-month period, several hundred thousand schoolchildren are victims of violent crimes in or near their schools, U. S. Dept. of Justice 1 (1989); House Select Committee Hearing 15 (1989). And, they report that this widespread violence in schools throughout the Nation significantly interferes with the quality of education in those schools. See, e. g., House Judiciary Committee Hearing 44 (1990) (linking school violence to dropout rate); U. S. Dept. of Health 118-119 (1978) (school-violence victims suffer academically); compare U. S. Dept, of Justice 1 (1991) (gun violence worst in. inner-city schools), with National Center 47 (dropout rates highest in inner cities). Based on reports such as these, Congress obviously could have thought that guns and learning are mutually exclusive. Senate Labor and Human Resources Committee Hearing 39 (1993); U. S. Dept. of Health 118, 123-124 (1978). Congress could therefore have found a substantial educational problem — teachers unable to teach, students unable to learn — and concluded that guns near schools contribute substantially to the size and scope of that problem.

*620Having found that guns in schools significantly undermine the quality of education in our Nation’s classrooms, Congress could also have found, given the effect of education upon interstate and foreign commerce, that gun-related violence in and around schools is a commercial, as well as a human, problem. Education, although far more than a matter of economics, has long been inextricably intertwined with the Nation’s economy. When this Nation began, most workers received their education in the workplace, typically (like Benjamin Franklin) as apprentices. See generally Seybolt; Rorabaugh; U. S. Dept. of Labor (1950). As late as the 1920’s, many workers still received general education directly from their employers — from large corporations, such as General Electric, Ford, and Goodyear, which created schools within their firms to help both the worker and the firm. See Bolino 15-25. (Throughout most of the 19th century fewer than one percent of all Americans received secondary education through attending a high school. See id., at 11.) As public school enrollment grew in the early 20th century, see Becker 218 (1993), the need for industry to teach basic educational skills diminished. But, the direct economic link between basic education and industrial productivity remained. Scholars estimate that nearly a quarter of America’s economic growth in the early years of this century is traceable directly to increased schooling, see Denison 243; that investment in “human capital” (through spending on education) exceeded investment in “physical capital” by a ratio of almost two to one, see Schultz 26 (1961); and that the economic returns to this investment in education exceeded the returns to conventional capital investment, see, e. g., Davis & Morrall 48-49.

In recent years the link between secondary education and business has strengthened, becoming both more direct and more important. Scholars on the subject report that technological changes and innovations in management techniques have altered the nature of the workplace so that more jobs now demand greater educational skills. See, e. g., MIT 32 *621(only about one-third of handtool company’s 1,000 workers were qualified to work with a new process that requires high-school-level reading and mathematical skills); Cyert & Mowery 68 (gap between wages of high school dropouts and better trained workers increasing); U. S. Dept. of Labor 41 (1981) (job openings for dropouts declining over time). There is evidence that “service, manufacturing or construction jobs are being displaced by technology that requires a better-educated worker or, more likely, are being exported overseas,” Gordon, Ponticell, & Morgan 26; that “workers with truly few skills by the year 2000 will find that only one job out of ten will remain,” ibid,.; and that

“[o]ver the long haul the best way to encourage the growth of high-wage jobs is to upgrade the skills of the work force. . . . [Bjetter-trained workers become more productive workers, enabling a company to become more competitive and expand.” Henkoff 60.

Increasing global competition also has made primary and secondary education economically more important. The portion of the American economy attributable to international trade nearly tripled between 1950 and 1980, and more than 70 percent of American-made goods now compete with imports. Marshall 205; Marshall & Tucker 33. Yet, lagging worker productivity has contributed to negative trade balances and to real hourly compensation that has fallen below wages in 10 other industrialized nations. See National Center 57; Handbook of Labor Statistics 561, 576 (1989); Neef & Kask 28, 31. At least some significant part of this serious productivity problem is attributable to students who emerge from classrooms without the reading or mathematical skills necessary to compete with their European or Asian counterparts, see, e. g., MIT 28, and, presumably, to high school dropout rates of 20 to 25 percent (up to 50 percent in inner cities), see, e. g., National Center 47; Chubb & Hanushek 215. Indeed, Congress has said, when writing other statutes, that *622“functionally or technologically illiterate” Americans in the work force “erod[e]” our economic “standing in the international marketplace,” Pub. L. 100-418, § 6002(a)(3), 102 Stat. 1469, and that “[o]ur Nation is ... paying the price of scientific and technological illiteracy, with our productivity declining, our industrial base ailing, and our global competitiveness dwindling,” H. R. Rep. No. 98-6, pt. 1, p. 19 (1983).

Finally, there is evidence that, today more than ever, many firms base their location decisions upon the presence, or absence, of a work force with a basic education. See Mac-Cormack, Newman, & Rosenfield 73; Coffee 296. Scholars on the subject report, for example, that today, “[h]igh speed communication and transportation make it possible to produce most products and services anywhere in the world,” National Center 38; that “[mjodern machinery and production methods can therefore be combined with low wage workers to drive costs down,” ibid.; that managers can perform “‘back office functions anywhere in the world now,’” and say that if they “ ‘can’t get enough skilled workers here’ ” they will “‘move the skilled jobs out of the country,’” id., at 41; with the consequence that “rich countries need better education and retraining, to reduce the supply of unskilled workers and to equip them with the skills they require for tomorrow’s jobs,” Survey of Global Economy 37. In light of this increased importance of education to individual firms, it is no surprise that half of the Nation’s manufacturers have become involved with setting standards and shaping curricula for local schools, Maturi 65-68, that 88 percent think this kind of involvement is important, id., at 68, that more than 20 States have recently passed educational reforms to attract new business, Overman 61-62, and that business magazines have begun to rank cities according to the quality of their schools, see Boyle 24.

The economic links I have just sketched seem fairly obvious. Why then is it not equally obvious, in light of those links, that a widespread, serious, and substantial physical *623threat to teaching and learning also substantially threatens the commerce to which that teaching and learning is inextricably tied? That is to say, guns in the hands of six percent of inner-city high school students and gun-related violence throughout a city’s schools must threaten the trade and commerce that those schools support. The only question, then, is whether the latter threat is (to use the majority’s terminology) “substantial.” The evidence of (1) the extent of the gun-related violence problem, see supra, at 619, (2) the extent of the resulting negative effect on classroom learning, see ibid., and (3) the extent of the consequent negative commercial effects, see supra, at 620-622, when taken together, indicate a threat to trade and commerce that is “substantial.” At the very least, Congress could rationally have concluded that the links are “substantial.”

Specifically, Congress could have found that gun-related violence near the classroom poses a serious economic threat (1) to consequently inadequately educated workers who must endure low paying jobs, see, e. g., National Center 29, and (2) to communities and businesses that might (in today’s “information society”) otherwise gain, from a well-educated work force, an important commercial advantage, see, e. g., Becker 10 (1992), of a kind that location near a railhead or harbor provided in the past. Congress might also have found these threats to be no different in kind from other threats that this Court has found within the commerce power, such as the threat that loan sharking poses to the “funds” of “numerous localities,” Perez v. United States, 402 U. S., at 157, and that unfair labor practices pose to instrumentalities of commerce, see Consolidated Edison Co. v. NLRB, 305 U. S. 197, 221-222 (1938). As I have pointed out, supra, at 618, Congress has written that “the occurrence of violent crime in school zones” has brought about a “decline in the quality of education” that “has an adverse impact on interstate commerce and the foreign commerce of the United States.” 18 U. S. C. §§ 922(q)(1)(F), (G). The violence-related facts, the educa*624tional facts, and the economic facts, taken together, make this conclusion rational. And, because under our case law, see supra, at 615-617; infra, at 627-628, the sufficiency of the constitutionally necessary Commerce Clause link between a crime of violence and interstate commerce turns simply upon size or degree, those same facts make the statute constitutional.

To hold this statute constitutional is not to “obliterate” the “distinction between what is national and what is local,” ante, at 567 (citation omitted; internal quotation marks omitted); nor is it to hold that the Commerce Clause permits the Federal Government to “regulate any activity that it found was related to the economic productivity of individual citizens,” to regulate “marriage, divorce, and child custody,” or to regulate any and all aspects of education. Ante, at 564. First, this statute is aimed at curbing a particularly acute threat to the educational process — the possession (and use) of life-threatening firearms in, or near, the classroom. The empirical evidence that I have discussed above unmistakably documents the special way in which guns and education are incompatible. See supra, at 619. This Court has previously recognized the singularly disruptive potential on interstate commerce that acts of violence may have. See Perez, supra, at 156-157. Second, the immediacy of the connection between education and the national economic well-being is documented by scholars and accepted by society at large in a way and to a degree that may not hold true for other social institutions. It must surely be the rare case, then, that a statute strikes at conduct that (when considered in the abstract) seems so removed from commerce, but which (practically speaking) has so significant an impact upon commerce.

In sum, a holding that the particular statute before us falls within the commerce power would not expand the scope of that Clause. Rather, it simply would apply pre-existing law to changing economic circumstances. See Heart of Atlanta *625Motel, Inc. v. United States, 379 U. S. 241, 251 (1964). It would recognize that, in today’s economic world, gun-related violence near the classroom makes a significant difference to our economic, as well as our social, well-being. In accordance with well-accepted precedent, such a holding would permit Congress “to act in terms of economic . . . realities,” would interpret the commerce power as “an affirmative power commensurate with the national needs,” and would acknowledge that the “commerce clause does not operate so as to render the nation powerless to defend itself against economic forces that Congress decrees inimical or destructive of the national economy.” North American Co. v. SEC, 327 U. S. 686, 705 (1946) (citing Swift & Co. v. United States, 196 U. S., at 398 (Holmes, J.)).

Ill

The majority’s holding — that §922 falls outside the scope of the Commerce Clause — creates three serious legal problems. First, the majority’s holding runs contrary to modern Supreme Court cases that have upheld congressional actions despite connections to interstate or foreign commerce that are less significant than the effect of school violence. In Perez v. United States, supra, the Court held that the Commerce Clause authorized a federal statute that makes it a crime to engage in loan sharking (“[e]xtortionate credit transactions”) at a local level. The Court said that Congress may judge that such transactions, “though purely mirastate, . . . affect interstate commerce.” 402 U. S., at 154 (emphasis added). Presumably, Congress reasoned that threatening or using force, say with a gun on a street corner, to collect a debt occurs sufficiently often so that the activity (by helping organized crime) affects commerce among the States. But, why then cannot Congress also reason that the threat or use of force — the frequent consequence of possessing a gun — in or near a school occurs sufficiently often so that such activity (by inhibiting basic education) affects *626commerce among the States? The negative impact upon the national economy of an inability to teach basic skills seems no smaller (nor less significant) than that of organized crime.

In Katzenbach v. McClung, 379 U. S. 294 (1964), this Court upheld, as within the commerce power, a statute prohibiting racial discrimination at local restaurants, in part because that discrimination discouraged travel by African Americans and in part because that discrimination affected purchases of food and restaurant supplies from other States. See id., at 300; Heart of Atlanta Motel, supra, at 274 (Black, J., concurring in McClung and in Heart of Atlanta). In Daniel v. Paul, 395 U. S. 298 (1969), this Court found an effect on commerce caused by an amusement park located several miles down a country road in the middle of Alabama — because some customers (the Court assumed), some food, 15 paddle-boats, and a juke box had come from out of state. See id., at 304-305, 308. In both of these cases, the Court understood that the specific instance of discrimination (at a local place of accommodation) was part of a general practice that, considered as a whole, caused not only the most serious human and social harm, but had nationally significant economic dimensions as well. See McClung, supra, at 301; Daniel, supra, at 307, n. 10. It is difficult to distinguish the case before us, for the same critical elements are present. Businesses are less likely to locate in communities where violence plagues the classroom. Families will hesitate to move to neighborhoods where students carry guns instead of books. (Congress expressly found in 1994 that “parents may decline to send their children to school” in certain areas “due to concern about violent crime and gun violence.” 18 U. S. C. § 922(q)(1)(E).) And (to look at the matter in the most narrowly commercial manner), interstate publishers therefore will sell fewer books and other firms will sell fewer school supplies where the threat of violence disrupts learning. Most importantly, like the local racial discrimination at issue in McClung and Daniel, the local instances here, taken *627together and considered as a whole, create a problem that causes serious human and social harm, but also has nationally significant economic dimensions.

In Wickard v. Filburn, 317 U. S. 111 (1942), this Court sustained the application of the Agricultural Adjustment Act of 1938 to wheat that Filburn grew and consumed on his own local farm because, considered in its totality, (1) homegrown wheat may be “induced by rising prices” to “flow into the market and check price increases,” and (2) even if it never actually enters the market, homegrown wheat nonetheless “supplies a need of the man who grew it which would otherwise be reflected by purchases in the open market” and, in that sense, “competes with wheat in commerce.” Id., at 128. To find both of these effects on commerce significant in amount, the Court had to give Congress the benefit of the doubt. Why would the Court, to find a significant (or “substantial”) effect here, have to give Congress any greater leeway? See also United States v. Women’s Sportswear Mfrs. Assn., 336 U. S. 460, 464 (1949) (“If it is interstate commerce that feels the pinch, it does not matter how local the operation which applies the squeeze”); Mandeville Island Farms, Inc. v. American Crystal Sugar Co., 334 U. S., at 236 (“[I]t is enough that the individual activity when multiplied into a general practice . . . contains a threat to the interstate economy that requires preventive regulation”).

The second legal problem the Court creates comes from its apparent belief that it can reconcile its holding with earlier cases by making a critical distinction between “commercial” and noncommercial “transaction[s].” Ante, at 561. That is to say, the Court believes the Constitution would distinguish between two local activities, each of which has an identical effect upon interstate commerce, if one, but not the other, is “commercial” in nature. As a general matter, this approach fails to heed this Court’s earlier warning not to turn “questions of the power of Congress” upon “formula[s]” that would give

*628“controlling force to nomenclature such as ‘production’ and ‘indirect’ and foreclose consideration of the actual effects of the activity in question upon interstate commerce.” Wickard, supra, at 120.

See also United States v. Darby, 312 U. S. 100, 116-117 (1941) (overturning the Court’s distinction between “production” and “commerce” in the child labor case, Hammer v. Dagenhart, 247 U. S. 251, 271-272 (1918)); Swift & Co. v. United States, 196 U. S., at 398 (Holmes, J.) (“[Cjommerce among the States is not a technical legal conception, but a practical one, drawn from the course of business”). Moreover, the majority’s test is not consistent with what the Court saw as the point of the cases that the majority now characterizes. Although the majority today attempts to categorize Perez, McClung, and Wickard as involving intrastate “economic activity,” ante, at 559, the Courts that decided each of those cases did not focus upon the economic nature of the activity regulated. Rather, they focused upon whether that activity affected interstate or foreign commerce. In fact, the Wickard Court expressly held that Filburn’s consumption of homegrown wheat, “though it may not be regarded as commerce,” could nevertheless be regulated — “whatever its nature” — so long as “it exerts a substantial economic effect on interstate commerce.” Wickard, supra, at 125 (emphasis added).

More importantly, if a distinction between commercial and noncommercial activities is to be made, this is not the ease in which to make it. The majority clearly cannot intend such a distinction to focus narrowly on an act of gun possession standing by itself, for such a reading could not be reconciled with either the civil rights cases (McClung and Daniel) or Perez — in each of those cases the specific transaction (the race-based exclusion, the use of force) was not itself “commercial.” And, if the majority instead means to distinguish generally among broad categories of activities, differentiating what is educational from what is commercial, then, as a *629practical matter, the line becomes almost impossible to draw. Schools that teach reading, writing, mathematics, and related basic skills serve both social and commercial purposes, and one cannot easily separate the one from the other. American industry itself has been, and is again, involved in teaching. See supra, at 620, 622. When, and to what extent, does its involvement make education commercial? Does the number of vocational classes that train students directly for jobs make a difference? Does it matter if the school is public or private, nonprofit or profit seeking? Does it matter if a city or State adopts a voucher plan that pays private firms to run a school? Even if one were to ignore these practical questions, why should there be a theoretical distinction between education, when it significantly benefits commerce, and environmental pollution, when it causes economic harm? See Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S. 264 (1981).

Regardless, if there is a principled distinction that could work both here and in future cases, Congress (even in the absence of vocational classes, industry involvement, and private management) could rationally conclude that schools fall on the commercial side of the line. In 1990, the year Congress enacted the statute before us, primary and secondary schools spent $230 billion — that is, nearly a quarter of a trillion dollars — which accounts for a significant portion of our $5.5 trillion gross domestic product for that year. See Statistical Abstract 147, 442 (1993). The business of schooling requires expenditure of these funds on student transportation, food and custodial services, books, and teachers’ salaries. See U. S. Dept. of Education 4, 7 (1993). These expenditures enable schools to provide a valuable service— namely, to equip students with the skills they need to survive in life and, more specifically, in the workplace. Certainly, Congress has often analyzed school expenditure as if it were a commercial investment, closely analyzing whether schools are efficient, whether they justify the significant resources *630they spend, and whether they can be restructured to achieve greater returns. See, e. g., S. Rep. No. 100-222, p. 2 (1987) (federal school assistance is “a prudent investment”); Senate Appropriations Committee Hearing (1994) (private sector management of public schools); cf. Chubb & Moe 185-229 (school choice); Hanushek 85-122 (performance based incentives for educators); Gibbs (decision in Hartford, Conn., to contract out public school system). Why could Congress, for Commerce Clause purposes, not consider schools as roughly analogous to commercial investments from which the Nation derives the benefit of an educated work force?

The third legal problem created by the Court’s holding is that it threatens legal uncertainty in an area of law that, until this case, seemed reasonably well settled. Congress has enacted many statutes (more than 100 sections of the United States Code), including criminal statutes (at least 25 sections), that use the words “affecting commerce” to define their scope, see, e. g., 18 U. S. C. § 844(i) (destruction of buildings used in activity affecting interstate commerce), and other statutes that contain no jurisdictional language at all, see, e. g., 18 U. S. C. § 922(o)(l) (possession of machineguns). Do these, or similar, statutes regulate noncommercial activities? If so, would that alter the meaning of “affecting commerce” in a jurisdictional element? Cf. United States v. Staszcuk, 517 F. 2d 53, 57-58 (CA7 1975) (en banc) (Stevens, J.) (evaluation of Congress’ intent “requires more than a consideration of the consequences of the particular transaction”). More importantly, in the absence of a jurisdictional element, are the courts nevertheless to take Wickard, 317 U. S., at 127-128, (and later similar cases) as inapplicable, and to judge the effect of a single noncommercial activity on interstate commerce without considering similar instances of the forbidden conduct? However these questions are eventually resolved, the legal uncertainty now created will restrict Congress’ ability to enact criminal laws aimed at criminal behavior that, considered problem by problem rather *631than instance by instance, seriously threatens the economic, as well as social, well-being of Americans.

IV

In sum, to find this legislation within the scope of the Commerce Clause would permit “Congress ... to act in terms of economic . . . realities.” North American Co. v. SEC, 327 U. S., at 705 (citing Swift & Co. v. United States, 196 U. S., at 398 (Holmes, J.)). It would interpret the Clause as this Court has traditionally interpreted it, with the exception of one wrong turn subsequently corrected. See Gibbons v. Ogden, 9 Wheat., at 195 (holding that the commerce power extends “to all the external concerns of the nation, and to those internal concerns which affect the States generally”); United States v. Darby, 312 U. S., at 116-117 (“The conclusion is inescapable that Hammer v. Dagenhart [the child labor case] was a departure from the principles which have prevailed in the interpretation of the Commerce Clause both before and since the decision .... It should be and now is overruled”). Upholding this legislation would do no more than simply recognize that Congress had a “rational basis” for finding a significant connection between guns in or near schools and (through their effect on education) the interstate and foreign commerce they threaten. For these reasons, I would reverse the judgment of the Court of Appeals. Respectfully, I dissent.

APPENDIX TO OPINION OF BREYER, J.

Congressional Materials

(in reverse chronological order)

Private Sector Management of Public Schools, Hearing before the Subcommittee on Labor, Héalth and Human Services, and Education and Related Agencies of the Senate Committee on Appropriations, 103d Cong., 2d Sess. (1994) (Senate Appropriations Committee Hearing (1994)). *632Children and Gun Violence, Hearings before the Subcommittee on Juvenile Justice of the Senate Committee on the Judiciary, 103d Cong., 1st Sess. (1993) (Senate Judiciary Committee Hearing (1993)).

Keeping Every Child Safe: Curbing the Epidemic of Violence, Joint Hearing before the Subcommittee on Children, Family, Drugs and Alcoholism of the Senate Committee on Labor and Human Resources and the House Select Committee on Children, Youth, and Families, 103d Cong., 1st Sess. (1993).

Recess from Violence: Making our Schools Safe, Hearing before the Subcommittee on Education, Arts and Humanities of the Senate Committee on Labor and Human Resources, 103d Cong., 1st Sess. (1993) (Senate Labor and Human Resources Committee Hearing (1993)).

Preparing for the Economy of the 21st Century, Hearings before the Subcommittee on Children, Family, Drugs and Alcoholism of the Senate Committee on Labor and Human Resources, 102d Cong., 2d Sess. (1992).

Children Carrying Weapons: Why the Recent Increase, Hearing before the Senate Committee on the Judiciary, 102d Cong., 2d Sess. (1992).

Youth Violence Prevention, Hearing before the Senate Committee on Governmental Affairs, 102d Cong., 2d Sess. (1992).

School Dropout Prevention and Basic Skills Improvement Act of 1990, Pub. L. 101-600, § 2(a)(2), 104 Stat. 3042.

Excellence in Mathematics, Science and Engineering Education Act of 1990, 104 Stat. 2883, 20 U. S. C. § 5301(a)(5) (1988 ed., Supp. V).

Oversight Hearing on Education Reform and American Business and the Implementation of the Hawkins-Stafford Amendments of 1988, Hearing before the Subcommittee on Elementary, Secondary, and Vocational Training of the *633House Committee on Education and Labor, 101st Cong., 2d Sess. (1990).

U. S. Power in a Changing World, Report Prepared for the Subcommittee on International Economic Policy and Trade of the House Committee on Foreign Affairs, 101st Cong., 2d Sess., 43-66 (1990).

Gun Free School Zones Act of 1990, Hearing before the Subcommittee on Crime of the House Committee on the Judiciary, 101st Cong., 2d Sess. (1990) (House Judiciary Committee Hearing (1990)).

Restoring American Productivity: The Role of Education and Human Resources, Hearing before the Senate Committee on Labor and Human Resources, 101st Cong., 1st Sess. (1989).

Children and Guns, Hearing before the House Select Committee on Children, Youth, and Families, 101st Cong., 1st Sess. (1989) (House Select Committee Hearing (1989)).

Education and Training for a Competitive America Act of 1988, Pub. L. 100-418, Title VI, 102 Stat. 1469.

S. Rep. No. 100-222 (1987).

Education and Training for American Competitiveness, Hearings before the House Committee on Education and Labor, 100th Cong., 1st Sess. (1987).

Competitiveness and the Quality of the American Work Force, Hearings before the Subcommittee on Education and Health of the Joint Economic Committee, 100th Cong., 1st Sess., pts. 1 and 2 (1987).

Oversight Hearing on Illiteracy, Joint Hearing before the Subcommittee on Elementary, Secondary, and Vocational Education of the House Committee on Education and Labor and the Subcommittee on Education, Arts and Humanities of the Senate Committee on Labor and Human Resources, 99th Cong., 2d Sess. (1986).

*634Oversight on Illiteracy in the United States, Hearings before the Subcommittee on Elementary, Secondary, and Vocational Education of the House Committee on Education and Labor, 99th Cong., 2d Sess. (1986).

Crime and Violence in the Schools, Hearing before the Subcommittee on Juvenile Justice of the Senate Committee on the Judiciary, 98th Cong., 2d Sess. (1984).

H. R. Rep. No. 98-6, pts. 1 and 2 (1983).

S. Rep. No. 98-151 (1983).

Education for Economic Security Act, Hearings before the Subcommittee on Education, Arts and Humanities of the Senate Committee on Labor and Human Resources, 98th Cong., 1st Sess. (1983).

Pub. L. 93-380, §825, 88 Stat. 602 (1974).

I. Clarke, Art and Industry: Instruction in Drawing Applied to the Industrial and Fine Arts, S. Exec. Doc. No. 209, 46th Cong., 2d Sess., pt. 2 (1891).

Other Federal Government Materials

(in reverse chronological order)

U. S. Dept, of Education, Office of Educational Research and Improvement, First Findings: The Educational Quality of the Workforce Employer Survey (Feb. 1995).

Economic Report of the President 108 (Feb. 1994).

U. S. Dept, of Commerce, Statistical Abstract of the United States (1993) (Statistical Abstract (1993)).

U. S. Dept, of Education, Office of Educational Research and Improvement, Public School Education Financing for School Year 1989-90 (June 1993) (U. S. Dept, of Education (1993)).

Economic Report of the President 101 (Feb. 1992).

U. S. Dept, of Labor, Secretary’s Commission on Achieving Necessary Skills, Skills and Tasks For Jobs: A SCANS- Report for America 2000 (1992).

*635U. S. Dept, of Labor, Employment and Training Administration, Beyond the School Doors: The Literacy Needs of Job Seekers Served by the U. S. Department of Labor (Sept. 1992).

U. S. Dept, of Justice, Bureau of Justice Statistics, School Crime: A National Crime Victimization Survey Report (Sept. 1991) (U. S. Dept, of Justice (1991)).

U. S. Dept, of Commerce, Bureau of Census, 1990 Census of Population: Education in the United States 474 (Jan. 1994).

U. S. Dept, of Justice, Office of Juvenile Justice and Delinquency Prevention, Weapons in Schools, OJJDP Bulletin 1 (Oct. 1989) (U. S. Dept, of Justice (1989)).

U. S. Dept, of Labor, Bureau of Labor Statistics, Handbook of Labor Statistics 281, 561, 576 (Aug. 1989) (Handbook of Labor Statistics (1989)).

Bishop, Incentives for Learning: Why American High School Students Compare So Poorly to their Counterparts Overseas, in 1 U. S. Dept, of Labor, Commission on Workforce Quality & Labor Market Efficiency, Investing in People 1 (Sept. 1989).

Rumberger & Levin, Schooling for the Modern Workplace, in 1 U. S. Dept, of Labor, Commission on Workforce Quality & Labor Market Efficiency, Investing in People 85 (Sept. 1989).

U. S. Dept, of Education and U. S. Department of Labor, The Bottom Line: Basic Skills in the Workplace 12 (1988).

U. S. Dept, of Labor, Employment and Training Administration, Estimating Educational Attainment of Future Employment Demand for States (Oct. 1981) (U. S. Dept, of Labor (1981)).

U. S. Dept, of Health, Education, and Welfare, National Institute of Education, Violent Schools — Safe Schools: The Safe School Study Report to Congress (1978) (U. S. Dept, of Health (1978)).

*636U. S. Dept, of Labor, Bureau of Apprenticeship, Apprenticeship Past and Present (1950) (U. S. Dept, of Labor (1950)).

Other Readily Available Materials

(in alphabetical order)

Akin & Garfinkel, School Expenditures and the Economic Returns to Schooling, 12 J. Human Resources 462 (1977).

American Council on Education, Business-Higher Education Forum, America’s Competitive Challenge: A Report to the President of the United States (Apr. 1983).

Applebome, Employers Wary of School System, N. Y. Times, Feb. 20, 1995, p. Al, col. 1.

Are Real Estate Firms Ready to Ride on the Infobahn?: Information Highway of Technology, 36 National Real Estate Investor, Oct. 1994, p. 6.

Aring, What the ‘V’ Word is Costing America’s Economy: Vocational Education, 74 Phi Delta Kappan 396 (1993).

G. Atkinson, The Economics of Education (1983).

Becker, The Adam Smith Address: Education, Labor Force Quality, and the Economy, Business Economics, Jan. 1992, p. 7 (Becker (1992)).

G. Becker, Human Capital (3d ed. 1993) (Becker (1993)).

I. Berg, Education and Jobs: The Great Training Robbery (1970).

Berryman, The Economy, Literacy Requirements, and At-Risk Adults, in Literacy and the Marketplace: Improving the Literacy of Low-Income Single Mothers 22 (June 1989).

Bishop, Is the Test Score Decline Responsible for the Productivity Growth Decline?, 79 Am. Econ. Rev. 178 (Mar. 1989).

Bishop, High School Performance and Employee Recruitment, 13 J. Labor Research 41 (1992).

Blackburn, What Can Explain the Increase in Earnings Inequality Among Males?, 29 Industrial Relations 441 (1990). *637Boissiere, Knight, & Sabot, Earnings, Schooling, Ability and Cognitive Skills, 75 Am. Econ. Rev. 1016 (1985).

A. Bolino, A Century of Human Capital by Education and Training (1989) (Bolino).

Boyle, Expansion Management’s Education Quotient, Economic Development Rev., Winter 1992, pp. 23-25 (Boyle).

Brandel, Wake Up Get Smart, New England Business, May 1991, p. 46.

Callahan & Rivara, Urban High School Youth and Handguns: A School-Based Survey, 267 JAMA 3038 (1992).

Card & Krueger, Does School Quality Matter? Returns to Education and the Characteristics of Public Schools in the United States, 100 J. Pol. Econ. 1 (1992).

A. Carnevale, America and the New Economy: How New Competitive Standards are Radically Changing American Workplaces (1991).

A. Carnevale and J. Porro, Quality Education: School Reform for the New American Economy 31-32 (1994).

Center to Prevent Handgun Violence, Caught in the Crossfire: A Report on Gun Violence in our Nation’s Schools (Sept. 1990).

Centers For Disease Control, Leads from the Morbidity and Mortality Weekly Report, 266 JAMA 2342 (1991) (Centers for Disease Control).

Chubb & Hanushek, Reforming Educational Reform, in Setting National Priorities 213 (H. Aaron ed. 1990) (Chubb & Hanushek).

J. Chubb & T. Moe, Politics, Markets, and America’s Schools (1990) (Chubb & Moe).

Coffee, Survey: Worker Skills, Training More Important in Site Selection, Site Selection, Apr. 1993, p. 296 (Coffee).

E. Cohn, The Economics of Education (rev. ed. 1979).

*638Council on Competitiveness, Competitiveness Index 5 (July 1994).

Council on Competitiveness, Elevating the Skills of the American Workforce (May 1993).

Council on Competitiveness, Governing America: A Competitiveness Policy Agenda for The New Administration 33-39 (1989).

R. Cyert & D. Mowery, Technology and Employment: Innovation and Growth in the U. S. Economy (1987) (Cyert & Mowery).

J. Cynoweth, Enhancing Literacy for Jobs and Productivity: Council of State Policy and Planning Agencies Report (1994).

J. Davis & J. Morrall, Evaluating Educational Investment (1974) (Davis & Morrall).

Denison, Education and Growth, in Economics and Education 237 (D. Rogers & H. Ruchlin eds. 1971) (Denison).

M. Dertouzos, R. Lester, & R. Solow, MIT Commission on Industrial Productivity, Made In America: Regaining the Productive Edge (1989).

A. DeYoung, Economics and American Education: A Historical and Critical Overview of the Impact of Economic Theories on Schooling in the United States (1989).

Downs, America’s Educational Failures Will Hurt Real Estate, National Real Estate Investor, Aug. 1988, p. 34.

Doyle, The Role of Private Sector Management in Public Education, 76 Phi Delta Kappan 128 (1994).

Education and Economic Development (C. Anderson & M. Bowman eds. 1965).

Education Commission of the States, Task Force on Education for Economic Growth, Action for Excellence (June 1983).

Educational Testing Service, Developing the Skills and Knowledge of the Workforce (1993).

*639Finding What Really Works in Education, Chief Executive, May 1994, p. 48.

Ganderton & Griffin, Impact of Child Quality on Earnings: The Productivity-of-Schooling Hypothesis, 11 Contemporary Policy Issues 39 (July 1993).

Garver, “Success Story!”: The Evolution of Economic Development in Broward County, Florida, 11 Economic Development Review 85 (Summer 1993).

Gibbs, Schools for Profit, Time, Oct. 17, 1994, p. 48 (Gibbs).

Gintis, Education, Technology, and the Characteristics of Worker Productivity, 61 Am. Econ. Rev. 266 (1971).

Glazer, A Human Capital Policy for the Cities, Public Interest, Summer 1993, p. 27.

Glazer, Violence in Schools: Can Anything be Done to Curb the Growing Violence?, The CQ Researcher, Sept. 11, 1992, pp. 785-808.

E. Gordon, J. Ponticell, & R. Morgan, Closing the Literacy Gap in American Business 23 (1991) (Gordon, Ponticell, & Morgan).

E. Hanushek, Making Schools Work: Improving Performance and Controlling Costs (1994) (Hanushek).

Henkoff, Where Will the Jobs Come From?, Fortune, Oct. 19, 1992, p. 58 (Henkoff).

Herbert, Reading, Writing, Reloading, N. Y. Times, Dec. 14, 1994, p. A23, col. 1.

Industry’s New Schoolhouse, N. Y. Times, Jan. 9, 1994, section 4A, p. 22, col. 3, Education Life Supp.

Introducing the EQ (Education Quotient), Expansion Management, Sept./Oct. 1991, pp. 18-24.

Investment in Education: The Equity-Efficiency Quandary (T. Schultz ed. 1972).

*640Itzkoff, America’s Unspoken Economic Dilemma: Falling Intelligence Levels, 18 J. Social, Pol. & Econ. Studies 311 (1993).

Johnson, The Private Sector Should Help U. S. Schools, Financier, Sept. 1991, p. 34.

Johnson & Stafford, Social Returns to Quantity and Quality of Schooling, 8 J. Human Resources 139 (1973).

W. Johnston & A. Packer, Workforce 2000: Work and Workers for the Twenty-first Century (1987).

Jorgenson, The Contribution of Education to U. S. Economic Growth, 1948-73, in Education and Economic Productivity 95 (E. Dean ed. 1984).

Kirkland, Are Service Jobs Good Jobs?, Fortune, June 10, 1985, p. 38.

J. Kozol, Illiterate America 13 (1985).

J. Kozol, Where Stands the Republic? Illiteracy: A Warning and a Challenge to the Nation’s Press 9 (1986).

M. Levin & A. Shank, Educational Investment in an Urban Society: Costs, Benefits, and Public Policy (1970).

Link & Ratledge, Social Returns to Quantity and Quality of Education: A Further Statement, 10 J. Human Resources 78 (1975).

Lyne, The Skills Gap: U. S. Work-Force Woes Complicate Business-Location Equation, Site Selection, Aug. 1992, p. 642.

MacCormack, Newman, & Rosenfield, The New Dynamics of Global Manufacturing Site Location, 35 Sloan Management Review, No. 4, p. 69 (1994) (MacCormack, Newman, & Rosenfield).

F. Machlup, Education and Economic Growth (1970).

Markey, The Labor Market Problems of Today’s High School Dropouts, Monthly Labor Review, June 1988, p. 36.

*641Marshall, The Implications of Internationalization for Labor Market Institutions and Industrial Relations Systems, in Rethinking Employment Policy 205 (D. Bawden & F. Skidmore eds. 1989) (Marshall).

R. Marshall & M. Tucker, Thinking for a Living: Work, Skills, and the Future of the American Economy 33 (1992) (Marshall & Tucker).

Maturi, The Workforce Lure: Education/Training Carries More Weight in Siting Decisions, Industry Week, May 16, 1994, pp. 65-68 (Maturi).

M. Maurice, F. Sellier, & J. Silvestre, The Social Foundations of Industrial Power: A Comparison of France and Germany (1986).

Mikulecky, Job Literacy: The Relationship Between School Preparation and Workplace Actuality, 17 Reading Research Quarterly 400 (1982).

Mikulecky & Ehlinger, The Influence of Metacognitive Aspects of Literacy on Job Performance of Electronics Technicians, 18 J. Reading Behavior 41 (1986).

MIT Commission on Industrial Productivity, Education and Training in the United States: Developing the Human Resources We Need for Technological Advance and Competitiveness, in 2 Working Papers of the MIT Commission on Industrial Productivity (1989) (MIT).

Mitchell, The Impact of International Trade on U. S. Employment, in American Labor in a Changing World Economy 5 (W. Morehouse ed. 1978).

Morgan & Sirageldin, A Note on the Quality Dimension in Education, 76 J. Pol. Econ. 1069 (1968).

National Academy of Education, Economic Dimensions of Education (1979).

National Center on Education and the Economy, America’s Choice: High Skills or Low Wages! (1990) (National Center). *642National Commission on Excellence in Education, A Nation at Risk 8-9 (Apr. 1983).

National Commission on Jobs and Small Business, Making America Work Again: Jobs, Small Business, and the International Challenge (1987).

National Governor’s Association, Making America Work 35-36, 77-96 (1987).

National Institute of Justice, Research in Brief, J. Toby, Violence in Schools 3 (Dec. 1983).

National School Safety Center, Weapons in Schools (May 1989).

Neef & Kask, Manufacturing Productivity and Labor Costs in 14 Economies, Monthly Labor Review, Dec. 1991, p. 24 (Neef & Kask).

Neff, Recharging U. S. Competitiveness: Perhaps We Should Use Germany’s Education System as a Benchmark, Industry Week, Jan. 20,1992, p. 21.

O’Connor, Education’s Significance as Quality-of-Life Location Factor Parallels Nationwide Reformist Movement, Site Selection Handbook, Aug. 1988, p. 846.

M. O’Donoghue, Economic Dimensions in Education (1971).

Organisation for Economic Co-operation and Development, Education and the Economy in a Changing Society (1989).

Overman, Skilled States Lure New Business, HRMagazine, Jan. 1994, pp. 61-62 (Overman).

Packer, Taking Action on the SCANS Report, Educational Leadership, Mar. 1992, p. 27.

R. Perlman, The Economics of Education: Conceptual Problems and Policy Issues (1973).

R. Price, Fighting Violence with All the Mushy Stuff,’ USA Today, May 9,1994, p. 9A.

D. Prothrow-Stith & M. Weissman, Deadly Consequences (1991).

*643G. Psacharopoulos, Returns to Education: An International Comparison (1973).

M. Rasell & E. Appelbaum, Investment in Learning: An Assessment of the Economic Return (1992).

Ray & Mickelson, Corporate Leaders, Resistant Youth, and School Reform in Sunbelt City: The Political Economy of Education, 37 Social Problems 178 (1990).

R. Reich, The Work of Nations (1991).

D. Riddle, Service-Led Growth: The Role of the Service Sector in World Development (1986).

W. Rorabaugh, The Craft Apprentice: From Franklin to the Machine Age in America (1986) (Rorabaugh).

Rumberger & Daymont, The Economic Value of Academic and Vocational Training Acquired in High School, in Youth and the Labor Market 157 (M. Borus ed. 1984).

Ruttenberg, The Limited Promise of Public Health Methodologies to Prevent Youth Violence, 103 Yale L. J. 1885 (1994).

Ryscavage & Henle, Earnings Inequality Accelerates in the 1980’s, Monthly Labor Review, Dec. 1990, p. 3.

T. Schultz, Education and Productivity (report prepared for the National Commission on Productivity, 1971).

Schultz, Investment in Human Capital, American Economic Review, Mar. 1961, p. 3, reprinted in 1 Economics of Education 13 (M. Blaug ed. 1968) (Schultz (1961)).

S. Seninger, Labor Force Policies for Regional Economic Development: The Role of Employment and Training Programs (1989).

R. Seybolt, Apprenticeship & Apprenticeship Education in Colonial New England & New York (1917) (Seybolt).

Sheley, McGee, & Wright, Gun-Related Violence in and Around Inner-City Schools, 146 Am. J. Diseases in Children 677 (1992) (Sheley, McGee, & Wright).

*644Stone & Boundy, School Violence: The Need for a Meaningful Response, 28 Clearinghouse Review 453 (1994).

Strane, Locating in Rural America Could be a Competitive Advantage, 12 Telemarketing, Oct. 1993, p. 92.

R. Sturm, How Do Education and Training Affect a Country’s Economic Performance? A Literature Survey (1993).

A Survey of The Global Economy, The Economist, Oct. 1, 1994, p. 37 (Survey of Global Economy).

Swaim & Podgursky, Do More-Educated Workers Fare Better Following Job Displacement?, Monthly Labor Review, Aug. 1989, p. 43.

Tremblay, The Impact of School and College Expenditures on the Wages of Southern and Non-Southern Workers, 7 J. Labor Research 201 (1986).

J. Vaizey, The Economics of Education (1973).

J. Vaizey, The Political Economy of Human Capital (1973).

Vallens, Global Economy May Dictate More Spending for Training, Modern Plastics, Nov. 1993, p. 19.

Wachtel, The Effect on Earnings of School and College Investment Expenditures, 58 Review of Economics & Statistics 326, 330 (1976).

Weiner & Siler, Trained to Order, Forbes, June 26, 1989, pp. 73-78.

L. Wheat, Urban Growth in the Nonmetropolitan South 65 (1976).

Wirth, Education and Work: The Choices We Face, Phi Delta Kappan, Jan. 1993, p. 361.

A. Wirth, Education and Work for the Year 2000 (1992).

L. Wise, Labor Market Policies and Employment Patterns in the United States 50 (1989).

*5Justice Stevens

delivered the opinion of the Court.

California is one of at least nine States that authorize the use of marijuana for medicinal purposes.1 The question presented in this case is whether the power vested in Congress by Article I, §8, of the Constitution “[t]o make all Laws which shall be necessary and proper for carrying into Execution” its authority to “regulate Commerce with foreign Nations, and among the several States” includes the power to prohibit the local cultivation and use of marijuana in compliance with California law.

I

California has been a pioneer in the regulation of marijuana. In 1913, California was one of the first States to prohibit the sale and possession of marijuana,2 and at the end of the century, California became the first State to authorize limited use of the drug for medicinal purposes. In 1996, California voters passed Proposition 215, now codified as the Compassionate Use Act of 1996.3 The proposition was de*6signed to ensure that “seriously ill” residents of the State have access to marijuana for medical purposes, and to encourage Federal and State Governments to take steps toward ensuring the safe and affordable distribution of the drug to patients in need.4 The Act creates an exemption from criminal prosecution for physicians,5 as well as for patients and primary caregivers who possess or cultivate marijuana for medicinal purposes with the recommendation or approval of a physician.6 A “primary caregiver” is a person who has consistently assumed responsibility for the housing, health, or safety of the patient.7

Respondents Angel Raich and Diane Monson are California residents who suffer from a variety of serious medical conditions and have sought to avail themselves of medical marijuana pursuant to the terms of the Compassionate Use *7Act. They are being treated by licensed, board-certified family practitioners, who have concluded, after prescribing a host of conventional medicines to treat respondents’ conditions and to alleviate their associated symptoms, that marijuana is the only drug available that provides effective treatment. Both women have been using marijuana as a medication for several years pursuant to their doctors’ recommendation, and both rely heavily on cannabis to function on a daily basis. Indeed, Raich’s physician believes that forgoing cannabis treatments would certainly cause Raich excruciating pain and could very well prove fatal.

Respondent Monson cultivates her own marijuana, and ingests the drug in a variety of ways including smoking and using a vaporizer. Respondent Raich, by contrast, is unable to cultivate her own, and thus relies on two caregivers, litigating as “John Does,” to provide her with locally grown marijuana at no charge. These caregivers also process the cannabis into hashish or keif, and Raich herself processes some of the marijuana into oils, balms, and foods for consumption.

On August 15, 2002, county deputy sheriffs and agents from the federal Drug Enforcement Administration (DEA) came to Monson’s home. After a thorough investigation, the county officials concluded that her use of marijuana was entirely lawful as a matter of California law. Nevertheless, after a 3-hour standoff, the federal agents seized and destroyed all six of her cannabis plants.

Respondents thereafter brought this action against the Attorney General of the United States and the head of the DEA seeking injunctive and declaratory relief prohibiting the enforcement of the federal Controlled Substances Act (CSA), 84 Stat. 1242, 21 U. S. C. § 801 et seq., to the extent it prevents them from possessing, obtaining, or manufacturing cannabis for their personal medical use. In their complaint and supporting affidavits, Raich and Monson described the severity of their afflictions, their repeatedly futile attempts *8to obtain relief with conventional medications, and the opinions of their doctors concerning their need to use marijuana. Respondents claimed that enforcing the CSA against them would violate the Commerce Clause, the Due Process Clause of the Fifth Amendment, the Ninth and Tenth Amendments of the Constitution, and the doctrine of medical necessity.

The District Court denied respondents’ motion for a preliminary injunction. Raich v. Ashcroft, 248 F. Supp. 2d 918 (ND Cal. 2003). Although the court found that the federal enforcement interests “wane[d]” when compared to the harm that California residents would suffer if denied access to medically necessary marijuana, it concluded that respondents could not demonstrate a likelihood of success on the merits of their legal claims. Id., at 931.

A divided panel of the Court of Appeals for the Ninth Circuit reversed and ordered the District Court to enter a preliminary injunction.8 Raich v. Ashcroft, 352 F. 3d 1222 (2003). The court found that respondents Had “demonstrated a strong likelihood of success on their claim that, as applied to them, the CSA is an unconstitutional exercise of Congress’ Commerce Clause authority.” Id., at 1227. The Court of Appeals distinguished prior Circuit cases upholding the CSA in the face of Commerce Clause challenges by focusing on what it deemed to be the “separate and distinct class of activities” at issue in this case: “the intrastate, noncommercial cultivation and possession of cannabis for personal medical purposes as recommended by a patient’s physician pursuant to valid California state law.” Id., at 1228. The *9court found the latter class of activities “different in kind from drug trafficking” because interposing a physician’s recommendation raises different health and safety concerns, and because “this limited use is clearly distinct from the broader illicit drug market — as well as any broader commercial market for medicinal marijuana — insofar as the medicinal marijuana at issue in this case is not intended for, nor does it enter, the stream of commerce.” Ibid.

The majority placed heavy reliance on our decisions in United States v. Lopez, 514 U. S. 549 (1995), and United States v. Morrison, 529 U. S. 598 (2000), as interpreted by recent Circuit precedent, to hold that this separate class of purely local activities was beyond the reach of federal power. In contrast, the dissenting judge concluded that the CSA, as applied to respondents, was clearly valid under Lopez and Morrison; moreover, he thought it “simply impossible to distinguish the relevant conduct surrounding the cultivation and use of the marijuana crop at issue in this case from the cultivation and use of the wheat crop that affected interstate commerce in Wickard v. Filburn” 352 F. 3d, at 1235 (opinion of Beam, J.).

The obvious importance of the case prompted our grant of certiorari. 542 U. S. 936 (2004). The case is made difficult by respondents’ strong arguments that they will suffer irreparable harm because, despite a congressional finding to the contrary, marijuana does have valid therapeutic purposes. The question before us, however, is not whether it is wise to enforce the statute in these circumstances; rather, it is whether Congress’ power to regulate interstate markets for medicinal substances encompasses the portions of those markets that are supplied with drugs produced and consumed locally. Well-settled law controls our answer. The CSA is a valid exercise of federal power, even as applied to the troubling facts of this case. We accordingly vacate the judgment of the Court of Appeals.

*10II

Shortly after taking office in 1969, President Nixon declared a national “war on drugs.”9 As the first campaign of that war, Congress set out to enact legislation that would consolidate various drug laws on the books into a comprehensive statute, provide meaningful regulation over legitimate sources of drugs to prevent diversion into illegal channels, and strengthen law enforcement tools against the traffic in illicit drugs.10 That effort culminated in the passage of the Comprehensive Drug Abuse Prevention and Control Act of 1970, 84 Stat. 1236.

This was not, however, Congress’ first attempt to regulate the national market in drugs. Rather, as early as 1906 Congress enacted federal legislation imposing labeling regulations on medications and prohibiting the manufacture or shipment of any adulterated or misbranded drug traveling in interstate commerce.11 Aside from these labeling restrictions, most domestic drug regulations prior to 1970 generally came in the guise of revenue laws, with the Department of the Treasury serving as the Federal Government’s primary enforcer.12 For example, the primary drug control law, before being repealed by the passage of the CSA, was the Harrison Narcotics Act of 1914, 38 Stat. 786 (repealed 1970). The Harrison Act sought to exert control over the possession and sale of narcotics, specifically cocaine and opiates, by requiring producers, distributors, and purchasers to register with the Federal Government, by assessing taxes against *11parties so registered, and by regulating the issuance of prescriptions.13

Marijuana itself was not significantly regulated by the Federal Government until 1937 when accounts of marijuana’s addictive qualities and physiological effects, paired with dissatisfaction with enforcement efforts at state and local levels, prompted Congress to pass the Marihuana Tax Act, 50 Stat. 551 (repealed 1970).14 Like the Harrison Act, the Marihuana Tax Act did not outlaw the possession or sale of marijuana outright. Rather, it imposed registration and reporting requirements for all individuals importing, producing, selling, or dealing in marijuana, and required the payment of annual taxes in addition to transfer taxes whenever the drug changed hands.15 Moreover, doctors wishing to prescribe marijuana for medical purposes were required to comply with rather burdensome administrative requirements.16 Noncompliance exposed traffickers to severe federal penalties, whereas compliance would often subject them to prosecution under state law.17 Thus, while the Marihuana Tax Act did not declare the drug illegal per se, the onerous administrative requirements, the prohibitively expensive taxes, and the risks attendant on compliance practically curtailed the marijuana trade.

Then in 1970, after declaration of the national “war on drugs,” federal drug policy underwent a significant transformation. A number of noteworthy events precipitated *12this policy shift. First, in Leary v. United States, 395 U. S. 6 (1969), this Court held certain provisions of the Marihuana Tax Act and other narcotics legislation unconstitutional. Second, at the end of his term, President Johnson fundamentally reorganized the federal drug control agencies. The Bureau of Narcotics, then housed in the Department of the Treasury, merged with the Bureau of Drug Abuse Control, then housed in the Department of Health, Education, and Welfare (HEW), to create the Bureau of Narcotics and Dangerous Drugs, currently housed in the Department of Justice.18 Finally, prompted by a perceived need to consolidate the growing number of piecemeal drug laws and to enhance federal drug enforcement powers, Congress enacted the Comprehensive Drug Abuse Prevention and Control Act.19

Title II of that Act, the CSA, repealed most of the earlier antidrug laws in favor of a comprehensive regime to combat the international and interstate traffic in illicit drugs. The main objectives of the CSA were to conquer drug abuse and to control the legitimate and illegitimate traffic in controlled substances.20 Congress was particularly concerned with the *13need to prevent the diversion of drugs from legitimate to illicit channels.21

To effectuate these goals, Congress devised a closed regulatory system making it unlawful to manufacture, distribute, dispense, or possess any controlled substance except in a manner authorized by the CSA. 21 U. S. C. §§ 841(a)(1), 844(a). The CSA categorizes all controlled substances into five schedules. §812. The drugs are grouped together based on their accepted medical uses, the potential for abuse, and their psychological and physical effects on the body. *14§§811, 812. Each schedule is associated with a distinct set of controls regarding the manufacture, distribution, and use of the substances listed therein. §§821-830. The CSA and its implementing regulations set forth strict requirements regarding registration, labeling and packaging, production quotas, drug security, and recordkeeping. Ibid.; 21 CFR § 1301 et seq. (2004).

In enacting the CSA, Congress classified marijuana as a Schedule I drug. 21 U. S. C. § 812(c). This preliminary classification was based, in part, on the recommendation of the Assistant Secretary of HEW “that marihuana be retained within schedule I at least until the completion of certain studies now underway.”22 Schedule I drugs are categorized as such because of their high potential for abuse, lack of any accepted medical use, and absence of any accepted safety for use in medically supervised treatment. § 812(b)(1). These three factors, in varying gradations, are also used to categorize drugs in the other four schedules. For example, Schedule II substances also have a high potential for abuse which may lead to severe psychological or physical dependence, but unlike Schedule I drugs, they have a currently accepted medical use. § 812(b)(2). By classifying marijuana as a Schedule I drug, as opposed to listing it on a lesser schedule, the manufacture, distribution, or possession of marijuana became a criminal offense, with the sole exception being use of the drug as part of a Food and Drug Administration preapproved research study. § § 823(f), 841(a)(1), 844(a); see also United States v. Oakland Cannabis Buyers’ Cooperative, 532 U. S. 483, 490 (2001).

The CSA provides for the periodic updating of schedules and delegates authority to the Attorney General, after consultation with the Secretary of Health and Human Services, to add, remove, or transfer substances to, from, or between *15schedules. §811. Despite considerable efforts to reschedule marijuana, it remains a Schedule I drug.23

1=1 1=( )=l

Respondents in this case do not dispute that passage of the CSA, as part of the Comprehensive Drug Abuse Prevention and Control Act, was well within Congress’ commerce power. Brief for Respondents 22,38. Nor do they contend that any provision or section of the CSA amounts to an unconstitutional exercise of congressional authority. Rather, respondents’ challenge is actually quite limited; they argue that the CSA’s categorical prohibition of the manufacture and possession of marijuana as applied to the intrastate manufacture and possession of marijuana for medical purposes pursuant to California law exceeds Congress’ authority under the Commerce Clause.

In assessing the validity of congressional regulation, none of our Commerce Clause cases can be viewed in isolation. As charted in considerable detail in United States v. Lopez, our understanding of the reach of the Commerce Clause, as well as Congress’ assertion of authority thereunder, has *16evolved over time.24 The Commerce Clause emerged as the Framers’ response to the central problem giving rise to the Constitution itself: the absence of any federal commerce power under the Articles of Confederation.25 For the first century of our history, the primary use of the Clause was to preclude the kind of discriminatory state legislation that had once been permissible.26 Then, in response to rapid industrial development and an increasingly interdependent national economy, Congress “ushered in a new era of federal regulation under the commerce power,” beginning with the enactment of the Interstate Commerce Act in 1887, 24 Stat. 379, and the Sherman Antitrust Act in 1890, 26 Stat. 209, as amended, 15 U. S. C. § 2 et seq.27

Cases decided during that “new era,” which now spans more than a century, have identified three general categories of regulation in which Congress is authorized to engage under its commerce power. First, Congress can regulate the channels of interstate commerce. Perez v. United States, 402 U.S. 146, 150 (1971). Second, Congress has authority to regulate and protect the instrumentalities of interstate commerce, and persons or things in interstate *17commerce. Ibid. Third, Congress has the power to regulate activities that substantially affect interstate commerce. Ibid.; NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1, 37 (1937). Only the third category is implicated in the case at hand.

Our case law firmly establishes Congress’ power to regulate purely local activities that are part of an economic “class of activities” that have a substantial effect on interstate commerce. See, e. g., Perez, 402 U. S., at 151; Wickard v. Filburn, 317 U. S. 111, 128-129 (1942). As we stated in Wick-ard, “even if appellee’s activity be local and though it may not be regarded as commerce, it may still, whatever its nature, be reached by Congress if it exerts a substantial economic effect on interstate commerce.” Id., at 125. We have never required Congress to legislate with scientific exactitude. When Congress decides that the “‘total incidence’ ” of a practice poses a threat to a national market, it may regulate the entire class. See Perez, 402 U. S., at 154-155 (“ ‘[W]hen it is necessary in order to prevent an evil to make the law embrace more than the precise thing to be prevented it may do so’ ” (quoting Westfall v. United States, 274 U. S. 256, 259 (1927))). In this vein, we have reiterated that when “ ‘a general regulatory statute bears a substantial relation to commerce, the de minimis character of individual instances arising under that statute is of no consequence.’ ” E. g., Lopez, 514 U. S., at 558 (quoting Maryland v. Wirtz, 392 U. S. 183, 196, n. 27 (1968); emphasis deleted).

Our decision in Wickard, 317 U. S. 111, is of particular relevance. In Wickard, we upheld the application of regulations promulgated under the Agricultural Adjustment Act of 1938, 52 Stat. 31, which were designed to control the volume of wheat moving in interstate and foreign commerce in order to avoid surpluses and consequent abnormally low prices. The regulations established an allotment of 11.1 acres for Filburn’s 1941 wheat crop, but he sowed 23 acres, intending to use the excess by consuming it on his own farm. Filburn *18argued that even though we had sustained Congress’ power to regulate the production of goods for commerce, that power did not authorize “federal regulation [of] production not intended in any part for commerce but wholly for consumption on the farm.” Wickard, 317 U. S., at 118. Justice Jackson’s opinion for a unanimous Court rejected this submission. He wrote:

“The effect of the statute before us is to restrict the amount which may be produced for market and the extent as well to which one may forestall resort to the market by producing to meet his own needs. That ap-pellee’s own contribution to the demand for wheat may be trivial by itself is not enough to remove him from the scope of federal regulation where, as here, his contribution, taken together with that of many others similarly situated, is far from trivial.” Id., at 127-128.

Wickard thus establishes that Congress can regulate purely intrastate activity that is not itself “commercial,” in that it is not produced for sale, if it concludes that failure to regulate that class of activity would undercut the regulation of the interstate market in that commodity.

The similarities between this case and Wickard are striking. Like the farmer in Wickard, respondents are cultivating, for home consumption, a fungible commodity for which there is an established, albeit illegal, interstate market.28 Just as the Agricultural Adjustment Act was designed “to *19control the volume [of wheat] moving in interstate and foreign commerce in order to avoid surpluses ...” and consequently control the market price, id., at 115, a primary purpose of the CSA is to control the supply and demand of controlled substances in both lawful and unlawful drug markets. See nn. 20-21, supra. In Wickard, we had no difficulty concluding that Congress had a rational basis for believing that, when viewed in the aggregate, leaving home-consumed wheat outside the regulatory scheme would have a substantial influence on price and market conditions. Here too, Congress had a rational basis for concluding that leaving home-consumed marijuana outside federal control would similarly affect price and market conditions.

More concretely, one concern prompting inclusion of wheat grown for home consumption in the 1938 Act was that rising market prices could draw such wheat into the interstate market, resulting in lower market prices. Wickard, 317 U. S., at 128. The parallel concern making it appropriate to include marijuana grown for home consumption in the CSA is the likelihood that the high demand in the interstate market will draw such marijuana into that market. While the diversion of homegrown wheat tended to frustrate the federal interest in stabilizing prices by regulating the volume of commercial transactions in the interstate market, the diversion of homegrown marijuana tends to frustrate the federal interest in eliminating commercial transactions in the interstate market in their entirety. In both cases, the regulation is squarely within Congress’ commerce power because production of the commodity meant for home consumption, be it wheat or marijuana, has a substantial effect on supply and demand in the national market for that commodity.29

*20Nonetheless, respondents suggest that Wickard differs from this case in three respects: (1) the Agricultural Adjustment Act, unlike the CSA, exempted small farming operations; (2) Wickard involved a “quintessential economic activity” — a commercial farm — whereas respondents do not sell marijuana; and (3) the Wickard record made it clear that the aggregate production of wheat for use on farms had a significant impact on market prices. Those differences, though factually accurate, do not diminish the precedential force of this Court’s reasoning.

The fact that Filburn’s own impact on the market was “trivial by itself” was not a sufficient reason for removing him from the scope of federal regulation. 317 U. S., at 127. That the Secretary of Agriculture elected to exempt even smaller farms from regulation does not speak to his power to regulate all those whose aggregated production was significant, nor did that fact play any role in the Court’s analysis. Moreover, even though Filburn was indeed a commercial farmer, the activity he was engaged in — the cultivation of wheat for home consumption — was not treated by the Court as part of his commercial farming operation.30 And while it is true that the record in the Wickard case itself established the causal connection between the production for local use and the national market, we have before us findings by Congress to the same effect.

Findings in the introductory sections of the CSA explain why Congress deemed it appropriate to encompass local activities within the scope of the CSA. See n. 20, supra. The *21submissions of the parties and the numerous amici all seem to agree that the national, and international, market for marijuana has dimensions that are fully comparable to those defining the class of activities regulated by the Secretary pursuant to the 1938 statute.31 Respondents nonetheless insist that the CSA cannot be constitutionally applied to their activities because Congress did not make a specific finding that the intrastate cultivation and possession of marijuana for medical purposes based on the recommendation of a physician would substantially affect the larger interstate marijuana market. Be that as it may, we have never required Congress to make particularized findings in order to legislate, see Lopez, 514 U. S., at 562; Perez, 402 U. S., at 156, absént a special concern such as the protection of free speech, see, e. g., Turner Broadcasting System, Inc. v. FCC, 512 U. S. 622, 664-668 (1994) (plurality opinion). While congressional findings are certainly helpful in reviewing the substance of a congressional statutory scheme, particularly when the connection to commerce is not self-evident, and while we will consider congressional findings in our analysis when they are available, the absence of particularized findings does not call into question Congress’ authority to legislate.32

*22In assessing the scope of Congress’ authority under the Commerce Clause, we stress that the task before us is a modest one. We need not determine whether respondents’ activities, taken in the aggregate, substantially affect interstate commerce in fact, but only whether a “rational basis” exists for so concluding. Lopez, 514 U. S., at 557; see also Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S. 264, 276-280 (1981); Perez, 402 U. S., at 155-156; Katzenbach v. McClung, 379 U. S. 294, 299-301 (1964); Heart of Atlanta Motel, Inc. v. United States, 379 U. S. 241, 252-253 (1964). Given the enforcement difficulties that attend distinguishing between marijuana cultivated locally and marijuana grown elsewhere, 21 U. S. C. §801(5), and concerns about diversion into illicit channels,33 we have no difficulty concluding that Congress had a rational basis for believing that failure to regulate the intrastate manufacture and possession of marijuana would leave a gaping hole in the CSA. Thus, as in Wickard, when it enacted comprehensive legislation to regulate the interstate market in a fungible commodity, Congress was acting well within its authority to “make all Laws which shall be necessary and proper” to “regulate Commerce . . . among the several States.” U. S. Const., Art. I, § 8. That the regulation ensnares some purely intrastate activity is of no moment. As we have done many times before, we refuse to excise individual components of that larger scheme.

*23IV

To support their contrary submission, respondents rely heavily on two of our more recent Commerce Clause cases. In their myopic focus, they overlook the larger context of modern-era Commerce Clause jurisprudence preserved by those cases. Moreover, even in the narrow prism of respondents’ creation, they read those cases far too broadly.

Those two cases, of course, are Lopez, 514 U. S. 549, and Morrison, 529 U. S. 598. As an initial matter, the statutory challenges at issue in those cases were markedly different from the challenge respondents pursue in the case at hand. Here, respondents ask us to excise individual applications of a concededly valid statutory scheme. In contrast, in both Lopez and Morrison, the parties asserted that a particular statute or provision fell outside Congress’ commerce power in its entirety. This distinction is pivotal for we have often reiterated that “[wjhere the class of activities is regulated and that class is within the reach of federal power, the courts have no power ‘to excise, as trivial, individual instances’ of the class.” Perez, 402 U. S., at 154 (quoting Wirtz, 392 U. S., at 193 (emphasis deleted)); see also Hodel, 452 U. S., at 308.

At issue in Lopez, 514 U. S. 549, was the validity of the Gun-Free School Zones Act of 1990, which was a brief, single-subject statute making it a crime for an individual to possess a gun in a school zone. 104 Stat. 4844-4845, 18 U. S. C. § 922(q)(1)(A). The Act did not regulate any economic activity and did not contain any requirement that the possession of a gun have any connection to past interstate activity or a predictable impact on future commercial activity. Distinguishing our earlier cases holding that comprehensive regulatory statutes may be validly applied to local conduct that does not, when viewed in isolation, have a significant impact on interstate commerce, we held the statute invalid. We explained:

*24“Section 922(q) is a criminal statute that by its terms has nothing to do with ‘commerce’ or any sort of economic enterprise, however broadly one might define those terms. Section 922(q) is not an essential part of a larger regulation of economic activity, in which the regulatory scheme could be undercut unless the intrastate activity were regulated. It cannot, therefore, be sustained under our cases upholding regulations of activities that arise out of or are connected with a commercial transaction, which viewed in the aggregate, substantially affects interstate commerce.” 514 U. S., at 561.

The statutory scheme that the Government is defending in this litigation is at the opposite end of the regulatory spectrum. As explained above, the CSA, enacted in 1970 as part of the Comprehensive Drug Abuse Prevention and Control Act, 84 Stat. 1242-1284, was a lengthy and detailed statute creating a comprehensive framework for regulating the production, distribution, and possession of five classes of “controlled substances.” Most of those substances — those listed in Schedules II through V — “have a useful and legitimate medical purpose and are necessary to maintain the health and general welfare of the American people.” 21 U. S. C. §801(1). The regulatory scheme is designed to foster the beneficial use of those medications, to prevent their misuse, and to prohibit entirely the possession or use of substances listed in Schedule I, except as a part of a strictly controlled research project.

While the statute provided for the periodic updating of the five schedules, Congress itself made the initial classifications. It identified 42 opiates, 22 opium derivatives, and 17 hallucinogenic substances as Schedule I drugs. 84 Stat. 1248. Marijuana was listed as the 10th item in the 3d subcategory. That classification, unlike the discrete prohibition established by the Gun-Free School Zones Act of 1990, was merely one of many “essential part[s] of a larger regulation of economic activity, in which the regulatory scheme could be undercut *25unless the intrastate activity were regulated.” Lopez, 514 U. S., at 561.34 Our opinion in Lopez casts no doubt on the validity of such a program.

Nor does this Court’s holding in Morrison, 529 U. S. 598. The Violence Against Women Act of 1994, 108 Stat. 1902, created a federal civil remedy for the victims of gender-motivated crimes of violence. 42 U. S. C. § 18981. The remedy was enforceable in both state and federal courts, and generally depended on proof of the violation of a state law. Despite congressional findings that such crimes had an adverse impact on interstate commerce, we held the statute unconstitutional because, like the statute in Lopez, it did not regulate economic activity. We concluded that “the noneco-nomic, criminal nature of the conduct at issue was central to our decision” in Lopez, and that our prior cases had identified a clear pattern of analysis: “‘Where economic activity substantially affects interstate commerce, legislation regulating that activity will be sustained.’”35 Morrison, 529 U. S., at 610.

Unlike those at issue in Lopez and Morrison, the activities regulated by the CSA are quintessentially economic. “Economics” refers to “the production, distribution, and consumption of commodities.” Webster’s Third New International *26Dictionary 720 (1966). The CSA is a statute that regulates the production, distribution, and consumption of commodities for which there is an established, and lucrative, interstate market. Prohibiting the intrastate possession or manufacture of an article of commerce is a rational (and commonly utilized) means of regulating commerce in that product.36 Such prohibitions include specific decisions requiring that a drug be withdrawn from the market as a result of the failure to comply with regulatory requirements as well as decisions excluding Schedule I drugs entirely from the market. Because the CSA is a statute that directly regulates economic, commercial activity, our opinion in Morrison casts no doubt on its constitutionality.

The Court of Appeals was able to conclude otherwise only by isolating a “separate and distinct” class of activities that it held to be beyond the reach of federal power, defined as “the intrastate, noncommercial cultivation, possession and use of marijuana for personal medical purposes on the advice of a physician and in accordance with state law.” 352 F. 3d, at 1229. The court characterized this class as “different in kind from drug trafficking.” Id., at 1228. The differences between the members of a class so defined and the principal traffickers in Schedule I substances might be sufficient to justify a policy decision exempting the narrower class from the coverage of the CSA. The question, however, is whether Congress’ contrary policy judgment, i. e., its decision to include this narrower “class of activities” within the larger regulatory scheme, was constitutionally deficient. We have no difficulty concluding that Congress acted rationally in determining that none of the characteristics making up the purported class, whether viewed individually or in the aggregate, compelled an exemption from the CSA; rather, the subdivided class of activities defined by the Court *27of Appeals was an essential part of the larger regulatory scheme.

First, the fact that marijuana is used “for personal medical purposes on the advice of a physician” cannot itself serve as a distinguishing factor. Id., at 1229. The CSA designates marijuana as contraband for any purpose; in fact, by characterizing marijuana as a Schedule I drug, Congress expressly found that the drug has no acceptable medical uses. Moreover, the CSA is a comprehensive regulatory regime specifically designed to regulate which controlled substances can be utilized for medicinal purposes, and in what manner. Indeed, most of the substances classified in the CSA “have a useful and legitimate medical purpose.” 21 U. S. C. §801(1). Thus, even if respondents are correct that marijuana does have accepted medical uses and thus should be redesignated as a lesser schedule drug,37 the CSA would still impose controls beyond what is required by California law. The CSA requires manufacturers, physicians, pharmacies, and other handlers of controlled substances to comply with statutory and regulatory provisions mandating registration with the DEA, compliance with specific production quotas, security controls to guard against diversion, recordkeeping and reporting obligations, and prescription requirements. See *28§§ 821-830; 21 CFR § 1301 et seq. (2004). Furthermore, the dispensing of new drugs, even when doctors approve their use, must await federal approval. United States v. Rutherford, 442 U. S. 544 (1979). Accordingly, the mere fact that marijuana — like virtually every other controlled substance regulated by the CSA — is used for medicinal purposes cannot possibly serve to distinguish it from the core activities regulated by the CSA.

Nor can it serve as an “objective marke[r]” or “objective facto[r]” to arbitrarily narrow the relevant class as the dissenters suggest, post, at 47 (opinion of O’Connor, J.); post, at 68 (opinion of Thomas, J.). More fundamentally, if, as the principal dissent contends, the personal cultivation, possession, and use of marijuana for medicinal purposes is beyond the “ ‘outer limits’ of Congress’ Commerce Clause authority,” post, at 42 (opinion of O’Connor, J.), it must also be true that such personal use of marijuana (or any other homegrown drug) for recreational purposes is also beyond those “ ‘outer limits,’ ” whether or not a State elects to authorize or even regulate such use. Justice Thomas’ separate dissent suffers from the same sweeping implications. That is, the dissenters’ rationale logically extends to place any federal regulation (including quality, prescription, or quantity controls) of any locally cultivated and possessed controlled substance for any purpose beyond the “‘outer limits’” of Congress’ Commerce Clause authority. One need not have a degree in economics to understand why a nationwide exemption for the vast quantity of marijuana (or other drugs) locally cultivated for personal use (which presumably would include use by friends, neighbors, and family members) may have a substantial impact on the interstate market for this extraordinarily popular substance. The congressional judgment that an exemption for such a significant segment of the total market would undermine the orderly enforcement of the entire regulatory scheme is entitled to a strong presumption of validity. Indeed, that judgment is not only rational, but “visible to the *29naked eye,” Lopez, 514 U. S., at 563, under any commonsense appraisal of the probable consequences of such an open-ended exemption.

Second, limiting the activity to marijuana possession and cultivation “in accordance with state law” cannot serve to place respondents’ activities beyond congressional reach. The Supremacy Clause unambiguously provides that if there is any conflict between federal and state law, federal law shall prevail. It is beyond peradventure that federal power over commerce is “ ‘superior to that of the States to provide for the welfare or necessities of their inhabitants,”’ however legitimate or dire those necessities may be. Wirtz, 392 U. S., at 196 (quoting Sanitary Dist. of Chicago v. United States, 266 U. S. 405, 426 (1925)). See also 392 U. S., at 195-196; Wickard, 317 U. S., at 124 (“ ‘[N]o form of state activity can constitutionally thwart the regulatory power granted by the commerce clause to Congress’ ”). Just as state acquiescence to federal regulation cannot expand the bounds of the Commerce Clause, see, e. g., Morrison, 529 U. S., at 661-662 (Breyer, J., dissenting) (noting that 38 States requested federal intervention), so too state action cannot circumscribe Congress’ plenary commerce power. See United States v. Darby, 312 U. S. 100, 114 (1941) (“That power can neither be enlarged nor diminished by the exercise or non-exercise of state power”).38

*30Respondents acknowledge this proposition, but nonetheless contend that their activities were not “an essential part of a larger regulatory scheme” because they had been “isolated by the State of California, and [are] policed by the State of California,” and thus remain “entirely separated from the market.” Tr. of Oral Arg. 27. The dissenters fall prey to similar reasoning. See n. 38, supra, at 26 and this page. The notion that California law h#s surgically excised a discrete activity that is hermetically sealed off from the larger interstate marijuana market is a dubious proposition, and, more importantly, one that Congress could have rationally rejected.

Indeed, that the California exemptions will have a significant impact on both the supply and demand sides of the market for marijuana is not just “plausible” as the principal dissent concedes, post, at 56 (opinion of O’Connor, J.), it is readily apparent. The exemption for physicians provides them with an economic incentive to grant their patients permission to use the drug. In contrast to most prescriptions for legal drugs, which limit the dosage and duration of the usage, under California law the doctor’s permission to *31recommend marijuana use is open-ended. The authority to grant permission whenever the doctor determines that a patient is afflicted with “any other illness for which marijuana provides relief,” Cal. Health & Safety Code Ann. § 11362.5(b)(1)(A) (West Supp. 2005), is broad enough to allow even the most scrupulous doctor to conclude that some recreational uses would be therapeutic.39 And our cases have taught us that there are some unscrupulous physicians who overprescribe when it is sufficiently profitable to do so.40

The exemption for cultivation by patients and caregivers can only increase the supply of marijuana in the California market.41 The likelihood that all such production will *32promptly terminate when patients recover or will precisely match the patients’ medical needs during their convalescence seems remote; whereas the danger that excesses will satisfy some of the admittedly enormous demand for recreational use seems obvious.42 Moreover, that the national and international narcotics trade has thrived in the face of vigorous criminal enforcement efforts suggests that no small number of unscrupulous people will make use of the California exemptions to serve their commercial ends whenever it is feasible to do so.43 Taking into account the fact that California is only one of at least nine States to have authorized the medical use of marijuana, a fact Justice O’Connor’s dissent conveniently disregards in arguing that the demonstrated effect on commerce while admittedly “plausible” is ultimately “unsubstantiated,” post, at 56, 55, Congress could have rationally concluded that the aggregate impact on the national market of all the transactions exempted from federal supervision is unquestionably substantial.

So, from the “separate and distinct” class of activities identified by the Court of Appeals (and adopted by the dissenters), we are left with “the intrastate, noncommercial cultivation, possession and use of marijuana.” 352 F. 3d, at 1229. Thus the case for the exemption comes down to the claim that a locally cultivated product that is used domestically *33rather than sold on the open market is not subject to federal regulation. Given the findings in the CSA and the undisputed magnitude of the commercial market for marijuana, our decisions in Wickard, v. Filburn and the later cases endorsing its reasoning foreclose that claim.

V

Respondents also raise a substantive due process claim and seek to avail themselves of the medical necessity defense. These theories of relief were set forth in their complaint but were not reached by the Court of Appeals. We therefore do not address the question whether judicial relief is available to respondents on these alternative bases. We do note, however, the presence of another avenue of relief. As the Solicitor General confirmed during oral argument, the statute authorizes procedures for the reclassification of Schedule I drugs. But perhaps even more important than these legal avenues is the democratic process, in which the voices of voters allied with these respondents may one day be heard in the halls of Congress. Under the present state of the law, however, the judgment of the Court of Appeals must be vacated. The case is remanded for further proceedings consistent with this opinion.

It is so ordered.

Justice Scalia,

concurring in the judgment.

I agree with the Court’s holding that the Controlled Substances Act (CSA) may validly be applied to respondents’ cultivation, distribution, and possession of marijuana for personal, medicinal use. I write separately because my understanding of the doctrinal foundation on which that holding rests is, if not inconsistent with that of the Court, at least more nuanced.

Since Perez v. United States, 402 U. S. 146 (1971), our cases have mechanically recited that the Commerce Clause permits congressional regulation of three categories: (1) the *34channels of interstate commerce; (2) the instrumentalities of interstate commerce, and persons or things in interstate commerce; and (3) activities that “substantially affect” interstate commerce. Id., at 150; see United States v. Morrison, 529 U. S. 598, 608-609 (2000); United States v. Lopez, 514 U. S. 549, 558-559 (1995); Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S. 264, 276-277 (1981). The first two categories are self-evident, since they are the ingredients of interstate commerce itself. See Gibbons v. Ogden, 9 Wheat. 1, 189-190 (1824). The third category, however, is different in kind, and its recitation without explanation is misleading and incomplete.

It is misleading because, unlike the channels, instrumen-talities, and agents of interstate commerce, activities that substantially affect interstate commerce are not themselves part of interstate commerce, and thus the power to regulate them cannot come from the Commerce Clause alone. Rather, as this Court has acknowledged since at least United States v. Coombs, 12 Pet. 72 (1838), Congress’s regulatory authority over intrastate activities that are not themselves part of interstate commerce (including activities that have a substantial effect on interstate commerce) derives from the Necessary and Proper Clause. Id., at 78; Katzenbach v. McClung, 379 U. S. 294, 301-302 (1964); United States v. Wrightwood Dairy Co., 315 U. S. 110, 119 (1942); Shreveport Rate Cases, 234 U. S. 342, 353 (1914); United States v. E. C. Knight Co., 156 U. S. 1, 39-40 (1895) (Harlan, J., dissenting).1 And the category of “activities that substantially affect interstate commerce,” Lopez, supra, at 559, is incomplete because the authority to enact laws necessary and proper for the regulation of interstate commerce is not limited to laws *35governing intrastate activities that substantially affect interstate commerce. Where necessary to make a regulation of interstate commerce effective, Congress may regulate even those intrastate activities that do not themselves substantially affect interstate commerce.

I

Our cases show that the regulation of intrastate activities may be necessary to and proper for the regulation of interstate commerce in two general circumstances. Most directly, the commerce power permits Congress not only to devise rules for the governance of commerce between States but also to facilitate interstate commerce by eliminating potential obstructions, and to restrict it by eliminating potential stimulants. See NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1, 36-37 (1937). That is why the Court has repeatedly sustained congressional legislation on the ground that the regulated activities had a substantial effect on interstate commerce. See, e. g., Hodel, supra, at 281 (surface coal mining); Katzenbach, supra, at 300 (discrimination by restaurants); Heart of Atlanta Motel, Inc. v. United States, 379 U. S. 241, 258 (1964) (discrimination by hotels); Mandeville Island Farms, Inc. v. American Crystal Sugar Co., 334 U. S. 219, 237 (1948) (intrastate price fixing); Board of Trade of Chicago v. Olsen, 262 U. S. 1, 40 (1923) (activities of a local grain exchange); Stafford v. Wallace, 258 U. S. 495, 517, 524-525 (1922) (intrastate transactions at stockyard). Lopez and Morrison recognized the expansive scope of Congress’s authority in this regard: “[T]he pattern is clear. Where economic activity substantially affects interstate commerce, legislation regulating that activity will be sustained.” Lopez, supra, at 560; Morrison, supra, at 610 (same).

This principle is not without limitation. In Lopez and Morrison, the Court — conscious of the potential of the “substantially affects” test to “ ‘obliterate the distinction between what is national and what is local,’ ” Lopez, supra, at 566-567 *36(quoting A. L. A. Schechter Poultry Corp. v. United States, 295 U. S. 495, 554 (1935)); see also Morrison, supra, at 615-616 — rejected the argument that Congress may regulate noneconomic activity based solely on the effect that it may have on interstate commerce through a remote chain of inferences. Lopez, supra, at 564-566; Morrison, supra, at 617-618. “[I]f we were to accept [such] arguments,” the Court reasoned in Lopez, “we are hard pressed to posit any activity by an individual that Congress is without power to regulate.” 514 U. S., at 564; see also Morrison, supra, at 615-616. Thus, although Congress’s authority to regulate intrastate activity that substantially affects interstate commerce is broad, it does not permit the Court to “pile inference upon inference,” Lopez, supra, at 567, in order to establish that noneconomic activity has a substantial effect on interstate commerce.

As we implicitly acknowledged in Lopez, however, Congress’s authority to enact laws necessary and proper for the regulation of interstate commerce is not limited to laws directed against economic activities that have a substantial effect on interstate commerce. Though the conduct in Lopez was not economic, the Court nevertheless recognized that it could be regulated as “an essential part of a larger regulation of economic activity, in which the regulatory scheme could be undercut unless the intrastate activity were regulated.” 514 U. S., at 561. This statement referred to those cases permitting the regulation of intrastate activities “which in a substantial way interfere with or obstruct the exercise of the granted power.” Wrightwood Dairy Co., supra, at 119; see also United States v. Darby, 312 U. S. 100, 118-119 (1941); Shreveport Rate Cases, supra, at 353. As the Court put it in Wrightwood Dairy, where Congress has the authority to enact a regulation of interstate commerce, “it possesses every power needed to make that regulation effective.” 315 U. S., at 118-119.

*37Although this power “to make . . . regulation effective” commonly overlaps with the authority to regulate economic activities that substantially affect interstate commerce,2 and may in some cases have been confused with that authority, the two are distinct. The regulation of an intrastate activity may be essential to a comprehensive regulation of interstate commerce even though the intrastate activity does not itself “substantially affect” interstate commerce. Moreover, as the passage from Lopez quoted above suggests, Congress may regulate even noneconomic local activity if that regulation is a necessary part of a more general regulation of interstate commerce. See Lopez, supra, at 561. The relevant question is simply whether the means chosen are “reasonably adapted” to the attainment of a legitimate end under the commerce power. See Darby, supra, at 121.

In Darby, for instance, the Court explained that “Congress, having ... adopted the policy of excluding from interstate commerce all goods produced for the commerce which do not conform to the specified labor standards,” 312 U. S., at 121, could not only require employers engaged in the production of goods for interstate commerce to conform to wage and hour standards, id., at 119-121, but could also require those employers to keep employment records in order to demonstrate compliance with the regulatory scheme, id., at 125. While the Court sustained the former regulation on the alternative ground that the activity it regulated could have a “great effect” on interstate commerce, id., at 122-123, it affirmed the latter on the sole ground that “[t]he require*38ment for records even of the intrastate transaction is an appropriate means to the legitimate end,” id., at 125.

As the Court said in the Shreveport Rate Cases, the Necessary and Proper Clause does not give “Congress ... the authority to regulate the internal commerce of a State, as such,” but it does allow Congress “to take all measures necessary or appropriate to” the effective regulation of the interstate market, “although intrastate transactions ... may thereby be controlled.” 234 U. S., at 353; see also Jones & Laughlin Steel Corp., 301 U. S., at 38 (the logic of the Shreveport Rate Cases is not limited to instrumentalities of commerce).

II

Today’s principal dissent objects that, by permitting Congress to regulate activities necessary to effective interstate regulation, the Court reduces Lopez and Morrison to little “more than a drafting guide.” Post, at 46 (opinion of O’Con-nor, J.). I think that criticism unjustified. Unlike the power to regulate activities that have a substantial effect on interstate commerce, the power to enact laws enabling effective regulation of interstate commerce can only be exercised in conjunction with congressional regulation of an interstate market, and it extends only to those measures necessary to make the interstate regulation effective. As Lopez itself states, and the Court affirms today, Congress may regulate noneconomic intrastate activities only where the failure to do so “could . . . undercut” its regulation of interstate commerce. See Lopez, supra, at 561; ante, at 18, 24-25. This is not a power that threatens to obliterate the line between “what is truly national and what is truly local.” Lopez, supra, at 567-568.

Lopez and Morrison affirm that Congress may not regulate certain “purely local” activity within the States based solely on the attenuated effect that such activity may have in the interstate market. But those decisions do not declare noneconomic intrastate activities to be categorically beyond *39the reach of the Federal Government. Neither case involved the power of Congress to exert control over intrastate activities in connection with a more comprehensive scheme of regulation; Lopez expressly disclaimed that it was such a case, 514 U. S., at 561, and Morrison did not even discuss the possibility that it was. (The Court of Appeals in Morrison made clear that it was not. See Brzonkala v. Virginia Polytechnic Inst., 169 F. 3d 820, 884-835 (CA4 1999) (en bane).) To dismiss this distinction as “superficial and formalistic,” see post, at 47 (O’Connor, J., dissenting), is to misunderstand the nature of the Necessary and Proper Clause, which empowers Congress to enact laws in effectuation of its enumerated powers that are not within its authority to enact in isolation. See McCulloch v. Maryland, 4 Wheat. 316, 421-422 (1819).

And there are other restraints upon the Necessary and Proper Clause authority. As Chief Justice Marshall wrote in McCulloch v. Maryland, even when the end is constitutional and legitimate, the means must be “appropriate” and “plainly adapted” to that end. Id., at 421. Moreover, they may not be otherwise “prohibited” and must be “consistent with the letter and spirit of the constitution.” Ibid. These phrases are not merely hortatory. For example, cases such as Printz v. United States, 521 U. S. 898 (1997), and New York v. United States, 505 U. S. 144 (1992), affirm that a law is not “ *proper for carrying into Execution the Commerce Clause’” “[w]hen [it] violates [a constitutional] principle of state sovereignty.” Printz, supra, at 923-924; see also New York, supra, at 166.

Ill

The application of these principles to the case before us is straightforward. In the CSA, Congress has undertaken to extinguish the interstate market in Schedule I controlled substances, including marijuana. The Commerce Clause unquestionably permits this. The power to regulate interstate commerce “extends not only to those regulations which aid, *40foster and protect the commerce, but embraces those which prohibit it.” Darby, 312 U. S., at 113. See also Hipolite Egg Co. v. United States, 220 U. S. 45, 58 (1911); Lottery Case, 188 U. S. 321, 354 (1903). To effectuate its objective, Congress has prohibited almost all intrastate activities related to Schedule I substances — both economic activities (manufacture, distribution, possession with the intent to distribute) and noneconomic activities (simple possession). See 21 U. S. C. §§ 841(a), 844(a). That simple possession is a non-economic activity is immaterial to whether it can be prohibited as a necessary part of a larger regulation. Rather, Congress’s authority to enact all of these prohibitions of intrastate controlled-substance activities depends only upon whether they are appropriate means of achieving the legitimate end of eradicating Schedule I substances from interstate commerce.

By this measure, I think the regulation must be sustained. Not only is it impossible to distinguish “controlled substances manufactured and distributed intrastate” from “controlled substances manufactured and distributed interstate,” but it hardly makes sense to speak in such terms. Drugs like marijuana are fungible commodities. As the Court explains, marijuana that is grown at home and possessed for personal use is never more than an instant from the interstate market — and this is so whether or not the possession is for medicinal use or lawful use under the laws of a particular State.3 *41See ante, at 25-33. Congress need not accept on faith that state law will be effective in maintaining a strict division between a lawful market for “medical” marijuana and the more general marijuana market. See ante, at 30, and n. 38. “To impose on [Congress] the necessity of resorting to means which it cannot control, which another government may furnish or withhold, would render its course precarious, the result of its measures uncertain, and create a dependence on other governments, which might disappoint its most important designs, and is incompatible with the language of the constitution.” McCulloch, 4 Wheat., at 424.

Finally, neither respondents nor the dissenters suggest any violation of state sovereignty of the sort that would render this regulation “inappropriate,” id., at 421 — except to argue that the CSA regulates an area typically left to state regulation. See post, at 48, 51 (opinion of O’Connor, J.); post, at 66 (opinion of Thomas, J.); Brief for Respondents 39-42. That is not enough to render federal regulation an inappropriate means. The Court has repeatedly recognized that, if authorized by the commerce power, Congress may regulate private endeavors “even when [that regulation] may pre-empt express state-law determinations contrary to the result which has commended itself to the collective wisdom of Congress.” National League of Cities v. Usery, 426 U. S. 833, 840 (1976); see Cleveland v. United States, 329 U. S. 14, 19 (1946); McCulloch, supra, at 424. At bottom, respond*42ents’ state-sovereignty argument reduces to the contention that federal regulation of the activities permitted by California’s Compassionate Use Act is not sufficiently necessary to be “necessary and proper” to Congress’s regulation of the interstate market. For the reasons given above and in the Court’s opinion, I cannot agree.

* * *

I thus agree with the Court that, however the class of regulated activities is subdivided, Congress could reasonably conclude that its objective of prohibiting marijuana from the interstate market “could be undercut” if those activities were excepted from its general scheme of regulation. See Lopez, 514 U. S., at 561. That is sufficient to authorize the application of the CSA to respondents.

Justice O’Connor,

with whom The Chief Justice and Justice Thomas join as to all but Part III,

dissenting.

We enforce the “outer limits” of Congress’ Commerce Clause authority not for their own sake, but to protect historic spheres of state sovereignty from excessive federal encroachment and thereby to maintain the distribution of power fundamental to our federalist system of government. United States v. Lopez, 514 U. S. 549, 557 (1995); NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1, 37 (1937). One of federalism’s chief virtues, of course, is that it promotes innovation by allowing for the possibility that “a single courageous State may, if its citizens choose, serve as a laboratory; and try novel social and economic experiments without risk to the rest of the country.” New State Ice Co. v. Liebmann, 285 U. S. 262, 311 (1932) (Brandeis, J., dissenting).

This case exemplifies the role of States as laboratories. The States’ core police powers have always included authority to define criminal law and to protect the health, safety, and welfare of their citizens. Brecht v. Abrahamson, 507 U. S. 619, 635 (1993); Whalen v. Roe, 429 U. S. 589, 603, *43n. 30 (1977). Exercising those powers, California (by ballot initiative and then by legislative codification) has come to its own conclusion about the difficult and sensitive question of whether marijuana should be available to relieve severe pain and suffering. Today the Court sanctions an application of the federal Controlled Substances Act that extinguishes that experiment, without any proof that the personal cultivation, possession, and use of marijuana for medicinal purposes, if economic activity in the first place, has a substantial effect on interstate commerce and is therefore an appropriate subject of federal regulation. In so doing, the Court announces a rule that gives Congress a perverse incentive to legislate broadly pursuant to the Commerce Clause — nestling questionable assertions of its authority into comprehensive regulatory schemes — rather than with precision. That rule and the result it produces in this case are irreconcilable with our decisions in Lopez, supra, and United States v. Morrison, 529 U. S. 598 (2000). Accordingly I dissent.

I

In Lopez, we considered the constitutionality of the Gun-Free School Zones Act of 1990, which made it a federal offense “for any individual knowingly to possess a firearm ... at a place that the individual knows, or has reasonable cause to believe, is a school zone,” 18 U. S. C. § 922(q)(2)(A). We explained that “Congress’ commerce authority includes the power to regulate those activities having a substantial relation to interstate commerce, i. e., those activities that substantially affect interstate commerce.” 514 U. S., at 558-559 (citation omitted). This power derives from the conjunction of the Commerce Clause and the Necessary and Proper Clause. Garcia v. San Antonio Metropolitan Transit Authority, 469 U. S. 528, 585-586 (1985) (O’Connor, J., dissenting) (explaining that United States v. Darby, 312 U. S. 100 (1941), United States v. Wrightwood Dairy Co., 315 U. S. 110 (1942), and Wickard v. Filburn, 317 U. S. 111 (1942), *44based their expansion of the commerce power on the Necessary and Proper Clause, and that “the reasoning of these cases underlies every recent decision concerning the reach of Congress to activities affecting interstate commerce”); ante, at 34 (Scalia, J., concurring in judgment). We held in Lopez that the Gun-Free School Zones Act could not be sustained as an exercise of that power.

Our decision about whether gun possession in school zones substantially affected interstate commerce turned on four considerations. Lopez, supra, at 559-567; see also Morrison, supra, at 609-613. First, we observed that our “substantial effects” cases generally have upheld federal regulation of economic activity that affected interstate commerce, but that §922(q) was a criminal statute having “nothing to do with ‘commerce’ or any sort of economic enterprise.” Lopez, 514 U. S., at 561. In this regard, we also noted that “[sjection 922(q) is not an essential part of a larger regulation of economic activity, in which the regulatory scheme could be undercut unless the intrastate activity were regulated. It cannot, therefore, be sustained under our cases upholding regulations of activities that arise out of or are connected with a commercial transaction, which viewed in the aggregate, substantially affects interstate commerce.” Ibid. Second, we noted that the statute contained no express jurisdictional requirement establishing its connection to interstate commerce. Ibid.

Third, we found telling the absence of legislative findings about the regulated conduct’s impact on interstate commerce. We explained that while express legislative findings are neither required nor, when provided, dispositive, findings “enable us to evaluate the legislative judgment that the activity in question substantially affect[s] interstate commerce, even though no such substantial effect [is] visible to the naked eye.” Id., at 563. Finally, we rejected as too attenuated the Government’s argument that firearm possession in school zones could result in violent crime which in turn could *45adversely affect the national economy. Id., at 563-567. The Constitution, we said, does not tolerate reasoning that would “convert congressional authority under the Commerce Clause to a general police power of the sort retained by the States.” Id., at 567. Later in Morrison, supra, we relied on the same four considerations to hold that §40302 of the Violence Against Women Act of 1994, 108 Stat. 1941, 42 U. S. C. § 13981, exceeded Congress’ authority under the Commerce Clause.

In my view, the case before us is materially indistinguishable from Lopez and Morrison when the same considerations are taken into account.

II

A

What is the relevant conduct subject to Commerce Clause analysis in this case? The Court takes its cues from Congress, applying the above considerations to the activity regulated by the Controlled Substances Act (CSA) in general. The Court’s decision rests on two facts about the CSA: (1) Congress chose to enact a single statute providing a comprehensive prohibition on the production, distribution, and possession of all controlled substances, and (2) Congress did not distinguish between various forms of intrastate noncommercial cultivation, possession, and use of marijuana. See 21 U. S. C. §§ 841(a)(1), 844(a). Today’s decision suggests that the federal regulation of local activity is immune to Commerce Clause challenge because Congress chose to act with an ambitious, all-encompassing statute, rather than piecemeal. In my view, allowing Congress to set the terms of the constitutional debate in this way, i. e., by packaging regulation of local activity in broader schemes, is tantamount to removing meaningful limits on the Commerce Clause.

The Court’s principal means of distinguishing Lopez from this case is to observe that the Gun-Free School Zones Act of 1990 was a “brief, single-subject statute,” ante, at 23, *46whereas the CSA is “a lengthy and detailed statute creating a comprehensive framework for regulating the production, distribution, and possession of five classes of ‘controlled substances,’ ” ante, at 24. Thus, according to the Court, it was possible in Lopez to evaluate in isolation the constitutionality of criminalizing local activity (there gun possession in school zones), whereas the local activity that the CSA targets (in this ease cultivation and possession of marijuana for personal medicinal use) cannot be separated from the general drug control scheme of which.it is a part.

Today’s decision allows Congress to regulate intrastate activity without check, so long as there is some implication by legislative design that regulating intrastate activity is essential (and the Court appears to equate “essential” with “necessary”) to the interstate regulatory scheme. Seizing upon our language in Lopez that the statute prohibiting gun possession in school zones was “not an essential part of a larger regulation of economic activity, in which the regulatory scheme could be undercut unless the intrastate activity were regulated,” 514 U. S., at 561, the Court appears to reason that the placement of local activity in a comprehensive scheme confirms that it is essential to that scheme. Ante, at 24-25. If the Court is right, then Lopez stands for nothing more than a drafting guide: Congress should have described the relevant crime as “transfer or possession of a firearm anywhere in the nation” — thus including commercial and noncommercial activity, and clearly encompassing some activity with assuredly substantial effect on interstate commerce. Had it done so, the majority hints, we would have sustained its authority to regulate possession of firearms in school zones; Furthermore, today’s decision suggests we would readily sustain a congressional decision to attach the regulation of intrastate activity to a pre-existing comprehensive (or even not-so-comprehensive) scheme. If so, the Court invites increased federal regulation of local activity even if, as it suggests, Congress would not enact a new inter*47state scheme exclusively for the sake of reaching intrastate activity, see ante, at 25, n. 84; ante, at 38-39 (Scalia, J., concurring in judgment).

I cannot agree that our decision in Lopez contemplated such evasive or overbroad legislative strategies with approval. Until today, such arguments have been made only in dissent. See Morrison, 529 U. S., at 657 (Breyer, J., dissenting) (given that Congress can regulate “‘an essential part of a larger regulation of economic activity,’ ” “can Congress save the present law by including it, or much of it, in a broader ‘Safe Transport’ or ‘Worker Safety’ act?”). Lopez and Morrison did not indicate that the constitutionality of federal regulation depends on superficial and formalistic distinctions. Likewise I did not understand our discussion of the role of courts in enforcing outer limits of the Commerce Clause for the sake of maintaining the federalist balance our Constitution requires, see Lopez, 514 U. S., at 557; id., at 578 (Kennedy, J., concurring), as a signal to Congress to enact legislation that is more extensive and more intrusive into the domain of state power. If the Court always defers to Congress as it does today, little may be left to the notion of enumerated powers.

The hard work for courts, then, is to identify objective markers for confining the analysis in Commerce Clause cases. Here, respondents challenge the constitutionality of the CSA as applied to them and those similarly situated. I agree with the Court that we must look beyond respondents’ own activities. Otherwise, individual litigants could always exempt themselves from Commerce Clause regulation merely by pointing to the obvious — that their personal activities do not have a substantial effect on interstate commerce. See Maryland v. Wirtz, 392 U. S. 183, 193 (1968); Wickard, 317 U. S., at 127-128. The task is to identify a mode of analysis that allows Congress to regulate more than nothing (by declining to reduce each case to its litigants) and less than everything (by declining to let Congress set the *48terms of analysis). The analysis may not be the same in every ease, for it depends on the regulatory scheme at issue and the federalism concerns implicated. See generally Lopez, 514 U. S., at 567; id., at 579 (Kennedy, J., concurring).

A number of objective markers are available to confine the scope of constitutional review here. Both federal and state legislation — including the CSA itself, the California Compassionate Use Act, and other state medical marijuana legislation — recognize that medical and nonmedical (i. e., recreational) uses of drugs are realistically distinct and can be segregated, and regulate them differently. See 21 U. S. C. § 812; Cal. Health & Safety Code Ann. §11362.5 (West Supp. 2005); ante, at 5 (opinion of the Court). Respondents challenge only the application of the CSA to medicinal use of marijuana. Cf. United States v. Raines, 362 U. S. 17, 20-22 (1960) (describing our preference for as-applied rather than facial challenges). Moreover, because fundamental structural concerns about dual sovereignty animate our Commerce Clause cases, it is relevant that this ease involves the interplay of federal and state regulation in areas of criminal law and social policy, where “States lay claim by right of history and expertise.” Lopez, supra, at 583 (Kennedy, J., concurring); see also Morrison, supra, at 617-619; Lopez, supra, at 580 (Kennedy, J., concurring) (“The statute before us upsets the federal balance to a degree that renders it an unconstitutional assertion of the commerce power, and our intervention is required”); cf. Garcia, 469 U. S., at 586 (O’Connor, J., dissenting) (“[Sjtate autonomy is a relevant factor in assessing the means by which Congress exercises its powers” under the Commerce Clause). California, like other States, has drawn on its reserved powers to distinguish the regulation of medicinal marijuana. To ascertain whether Congress’ encroachment is constitutionally justified in this case, then, I would focus here on the personal cultivation, possession, and use of marijuana for medicinal purposes.

*49B

Having thus defined the relevant conduct, we must determine whether, under our precedents, the conduct is economic and, in the aggregate, substantially affects interstate commerce. Even if intrastate cultivation and possession of marijuana for one’s own medicinal use can properly be characterized as economic, and I question whether it can, it has not been shown that such activity substantially affects interstate commerce. Similarly, it is neither self-evident nor demonstrated that regulating such activity is necessary to the interstate drug control scheme.

The Court’s definition of economic activity is breathtaking. It defines as economic any activity involving the production, distribution, and consumption of commodities. And it appears to reason that when an interstate market for a commodity exists, regulating the intrastate manufacture or possession of that commodity is constitutional either because that intrastate activity is itself economic, or because regulating it is a rational part of regulating its market. Putting to one side the problem endemic to the Court’s opinion — the shift in focus from the activity at issue in this case to the entirety of what the CSA regulates, see Lopez, supra, at 565 (“depending on the level of generality, any activity can be looked upon as commercial”) — the Court’s definition of economic activity for purposes of Commerce Clause jurisprudence threatens to sweep all of productive human activity into federal regulatory reach.

The Court uses a dictionary definition of economics to skirt the real problem of drawing a meaningful line between “what is national and what is local,” Jones & Laughlin Steel, 301 U. S., at 37. It will not do to say that Congress may regulate noncommercial activity simply because it may have an effect on the demand for commercial goods, or because the noncommercial endeavor can, in some sense, substitute for commercial activity. Most commercial goods or services have some sort of privately producible analogue. Home care *50substitutes for daycare. Charades games substitute for movie tickets. Backyard or windowsili gardening substitutes for going to the supermarket. To draw the line wherever private activity affects the demand for market goods is to draw no line at all, and to declare everything economic. We have already rejected the result that would follow — a federal police power. Lopez, supra, at 564.

In Lopez and Morrison, we suggested that economic activity usually relates directly to commercial activity. See Morrison, 529 U. S., at 611, n. 4 (intrastate activities that have been within Congress’ power to regulate have been “of an apparent commercial character”); Lopez, 514 U. S., at 561 (distinguishing the Gun-Free School Zones Act of 1990 from “activities that arise out of or are connected with a commercial transaction”). The homegrown cultivation and personal possession and use of marijuana for medicinal purposes has no apparent commercial character. Everyone agrees that the marijuana at issue in this case was never in the stream of commerce, and neither were the supplies for growing it. (Marijuana is highly unusual among the substances subject to the CSA in that it can be cultivated without any materials that have traveled in interstate commerce.) Lopez makes clear that possession is not itself commercial activity. Ibid. And respondents have not come into possession by means of any commercial transaction; they have simply grown, in their own homes, marijuana for their own use, without acquiring, buying, selling, or bartering a thing of value. Cf. id., at 583 (Kennedy, J., concurring) (“The statute now before us forecloses the States from experimenting . . . and it does so by regulating an activity beyond the realm of commerce in the ordinary and usual sense of that term”).

The Court suggests that Wickard, which we have identified as “perhaps the most far reaching example of Commerce Clause authority over intrastate activity,” Lopez, supra, at 560, established federal regulatory power over any home consumption of a commodity for which a national market ex*51ists. I disagree. Wickard involved a challenge to the Agricultural Adjustment Act of 1938 (AAA), which directed the Secretary of Agriculture to set national quotas on wheat production, and penalties for excess production. 317 U. S., at 115-116. The AAA itself confirmed that Congress made an explicit choice not to reach — and thus the Court could not possibly have approved of federal control over — small-scale, noncommercial wheat farming. In contrast to the CSA’s limitless assertion of power, Congress provided an exemption within the AAA for small producers. When Filburn planted the wheat at issue in Wickard, the statute exempted plantings less than 200 bushels (about six tons), and when he harvested his wheat it exempted plantings less than six acres. Id., at 130, n. 30. Wickard, then, did not extend Commerce Clause authority to something as modest as the home cook’s herb garden. This is not to say that Congress may never regulate small quantities of commodities possessed or produced for personal use, or to deny that it sometimes needs to enact a zero tolerance regime for such commodities. It is merely to say that Wickard did not hold or imply that small-scale production of commodities is always economic, and automatically within Congress’ reach.

Even assuming that economic activity is at issue in this case, the Government has made no showing in fact that the possession and use of homegrown marijuana for medical purposes, in California or elsewhere, has a substantial effect on interstate commerce. Similarly, the Government has not shown that regulating such activity is necessary to an interstate regulatory scheme. Whatever the specific theory of “substantial effects” at issue (i. e., whether the activity substantially affects interstate commerce, whether its regulation is necessary to an interstate regulatory scheme, or both), a concern for dual sovereignty requires that Congress’ excursion into the traditional domain of States be justified.

That is why characterizing this as a case about the Necessary and Proper Clause does not change the analysis signifi*52cantly. Congress must exercise its authority under the Necessary and Proper Clause in a manner consistent with basic constitutional principles. Garcia, 469 U. S., at 585 (O’Connor, J., dissenting) (“It is not enough that the ‘end be legitimate’; the means to that end chosen by Congress must not contravene the spirit of the Constitution”). As Justice Scalia recognizes, see ante, at 39 (opinion concurring in judgment), Congress cannot use its authority under the Clause to contravene the principle of state sovereignty embodied in the Tenth Amendment. Likewise, that authority must be used in a manner consistent with the notion of enumerated powers — a structural principle that is as much part of the Constitution as the Tenth Amendment’s explicit textual command. Accordingly, something more than mere assertion is required when Congress purports to have power over local activity whose connection to an interstate market is not self-evident. Otherwise, the Necessary and Proper Clause will always be a back door for unconstitutional federal regulation. Cf. Printz v. United States, 521 U. S. 898, 923 (1997) (the Necessary and Proper Clause is “the last, best hope of those who defend ultra vires congressional action”). Indeed, if it were enough in “substantial effects” cases for the Court to supply conceivable justifications for intrastate regulation related to an interstate market, then we could have surmised in Lopez that guns in school zones are “never more than an instant from the interstate market” in guns already subject to extensive federal regulation, ante, at 40 (Scalia, J., concurring in judgment), recast Lopez as a Necessary and Proper Clause case, and thereby upheld the Gun-Free School Zones Act of 1990. (According to the Court’s and the concurrence’s logic, for example, the Lopez Court should have reasoned that the prohibition on gun possession in school zones could be an appropriate means of effectuating a related prohibition on “selling]” or “deliver-ting]” firearms or ammunition to “any individual who the licensee knows or has reasonable cause to believe is less than *53eighteen years of age.” 18 U. S. C. § 922(b)(1) (1988 ed., Supp. II).)

There is simply no evidence that homegrown medicinal marijuana users constitute, in the aggregate, a sizable enough class to have a discernable, let alone substantial, impact on the national illicit drug market — or otherwise to threaten the CSA regime. Explicit evidence is helpful when substantial effect is not “visible to the naked eye.” See Lopez, 514 U. S., at 563. And here, in part because common sense suggests that medical marijuana users may be limited in number and that California’s Compassionate Use Act and similar state legislation may well isolate activities relating to medicinal marijuana from the illicit market, the effect of those activities on interstate drug traffic is not self-evidently substantial.

In this regard, again, this case is readily distinguishable from Wickard. To decide whether the Secretary could regulate local wheat farming, the Court looked to “the actual effects of the activity in question upon interstate commerce.” 317 U. S., at 120. Critically, the Court was able to consider “actual effects” because the parties had “stipulated a summary of the economics of the wheat industry.” Id., at 125. After reviewing in detail the picture of the industry provided in that summary, the Court explained that consumption of homegrown wheat was the most variable factor in the size of the national wheat crop, and that on-site consumption could have the effect of varying the amount of wheat sent to market by as much as 20 percent. Id., at 127. With real numbers at hand, the Wickard Court could easily conclude that “a factor of such volume and variability as home-consumed wheat would have a substantial influence on price and market conditions” nationwide. Id., at 128; see also id., at 128-129 (“This record leaves us in no doubt” about substantial effects).

The Court recognizes that “the record in the Wickard case itself established the causal connection between the produc*54tion for local use and the national market” and argues that “we have before us findings by Congress to the same effect” Ante, at 20 (emphasis added). The Court refers to a series of declarations in the introduction to the CSA saying that (1) local distribution and possession of controlled substances causes “swelling” in interstate traffic; (2) local production and distribution cannot be distinguished from interstate production and distribution; (3) federal control over intrastate incidents “is essential to the effective control” over interstate drug trafficking. 21U. S. C. §§ 801(1)-(6). These bare declarations cannot be compared to the record before the Court in Wickard.

They amount to nothing more than a legislative insistence that the regulation of controlled substances must be absolute. They are asserted without any supporting evidence— descriptive, statistical, or otherwise. “[S]imply because Congress may conclude that a particular activity substantially affects interstate commerce does not necessarily make it so.” Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S. 264, 311 (1981) (Rehnquist, J., concurring in judgment). Indeed, if declarations like these suffice to justify federal regulation, and if the Court today is right about what passes rationality review before us, then our decision in Morrison should have come out the other way. In that case, Congress had supplied numerous findings regarding the impact gender-motivated violence had on the national economy. 529 U. S., at 614; id., at 628-636 (Souter, J., dissenting) (chronicling findings). But, recognizing that ““‘[w]hether particular operations affect interstate commerce sufficiently to come under the constitutional power of Congress to regulate them is ultimately a judicial rather than a legislative question,”’” we found Congress’ detailed findings inadequate. Id., at 614 (quoting Lopez, supra, at 557, n. 2, in turn quoting Heart of Atlanta Motel, Inc. v. United States, 379 U. S. 241, 273 (1964) (Black, J., concurring)). If, as the Court claims, today’s decision does not *55break with precedent, how can it be that voluminous findings, documenting extensive hearings about the specific topic of violence against women, did not pass constitutional muster in Morrison, while the CSA’s abstract, unsubstantiated, generalized findings about controlled substances do?

In particular, the CSA’s introductory declarations are too vague and unspecific to demonstrate that the federal statutory scheme will be undermined if Congress cannot exert power over individuals like respondents. The declarations are not even specific to marijuana. (Facts about substantial effects may be developed in litigation to compensate for the inadequacy of Congress’ findings; in part because this case comes to us from the grant of a preliminary injunction, there has been no such development.) Because here California, like other States, has carved out a limited class of activity for distinct regulation, the inadequacy of the CSA’s findings is especially glaring. The California Compassionate Use Act exempts from other state drug laws patients and then-caregivers “who posses[s] or cultivate] marijuana for the personal medical purposes of the patient upon the written or oral recommendation or approval of a physician” to treat a list of serious medical conditions. Cal. Health & Safety Code Ann. §§ 11362.5(d), 11362.7(h) (West Supp. 2005) (emphasis added). Compare ibid, with, e.g., § 11357(b) (West 1991) (criminalizing marijuana possession in excess of 28.5 grams); §11358 (criminalizing marijuana cultivation). The Act specifies that it should not be construed to supersede legislation prohibiting persons from engaging in acts dangerous to others, or to condone the diversion of marijuana for nonmedical purposes. § 11362.5(b)(2) (West Supp. 2005). To promote the Act’s operation and to facilitate law enforcement, California recently enacted an identification card system for qualified patients. §§ 11362.7-11362.83. We generally assume States enforce their laws, see Riley v. National Federation of Blind of N. C., Inc., 487 U. S. 781, 795 (1988), and have no reason to think otherwise here.

*56The Government has not overcome empirical doubt that the number of Californians engaged in personal cultivation, possession, and use of medical marijuana, or the amount of marijuana they produce, is enough to threaten the federal regime. Nor has it shown that Compassionate Use Act marijuana users have been or are realistically likely to be responsible for the drug’s seeping into the market in a significant way. The Government does cite one estimate that there were over 100,000 Compassionate Use Act users in California in 2004, Reply Brief for Petitioners 16, but does not explain, in terms of proportions, what their presence means for the national illicit drug market. See generally Wirtz, 392 U. S., at 196, n. 27 (Congress cannot use “a relatively trivial impact on commerce as an excuse for broad general regulation of state or private activities”); cf. General Accounting Office, Marijuana: Early Experiences with Four States’ Laws That Allow Use for Medical Purposes 21-23 (Rep. No. 03-189, Nov. 2002), http://www.gao.gov/new.items/ d03189.pdf (as visited June 3, 2005, and available in Clerk of Court’s case file) (in four California counties before the identification card system was enacted, voluntarily registered medical marijuana patients were less than 0.5 percent of the population; in Alaska, Hawaii, and Oregon, statewide medical marijuana registrants represented less than 0.05 percent of the States’ populations). It also provides anecdotal evidence about the CSA’s enforcement. See Reply Brief for Petitioners 17-18. The Court also offers some arguments about the effect of the Compassionate Use Act on the national market. It says that the California statute might be vulnerable to exploitation by unscrupulous physicians, that Compassionate Use Act patients may overproduce, and that the history of the narcotics trade shows the difficulty of cordoning off any drug use from the rest of the market. These arguments are plausible; if borne out in fact they could justify prosecuting Compassionate Use Act patients under the federal CSA. But, without substantiation, *57they add little to the CSA’s conclusory statements about diversion, essentiality, and market effect. Piling assertion upon assertion does not, in my view, satisfy the substantiality test of Lopez and Morrison.

Ill

We would do well to recall how James Madison, the father of the Constitution, described our system of joint sovereignty to the people of New York: “The powers delegated by the proposed Constitution to the federal government are few and defined. Those which are to remain in the State governments are numerous and indefinite. . . . The powers reserved to the several States will extend to all the objects which, in the ordinary course of affairs, concern the lives, liberties, and properties of the people, and the internal order, improvement, and prosperity of the State.” The Federalist No. 45, pp. 292-293 (C. Rossiter ed. 1961).

Relying on Congress’ abstract assertions, the Court has endorsed making it a federal crime to grow small amounts of marijuana in one’s own home for one’s own medicinal use. This overreaching stifles an express choice by some States, concerned for the lives and liberties of their people, to regulate medical marijuana differently. If I were a California citizen, I would not have voted for the medical marijuana ballot initiative; if I were a California legislator I would not have supported the Compassionate Use Act. But whatever the wisdom of California’s experiment with medical marijuana, the federalism principles that have driven our Commerce Clause cases require that room for experiment be protected in this case. For these reasons I dissent.

Justice Thomas,

dissenting.

Respondents Diane Monson and Angel Raich use marijuana that has never been bought or sold, that has never crossed state lines, and that has had no demonstrable effect on the national market for marijuana. If Congress can reg*58ulate this under the Commerce Clause, then it can regulate virtually anything — and the Federal Government is no longer one of limited and enumerated powers.

I

Respondents’ local cultivation and consumption of marijuana is not “Commerce . . . among the several States.” U. S. Const., Art. I, § 8, cl. 3. By holding that Congress may regulate activity that is neither interstate nor commerce under the Interstate Commerce Clause, the Court abandons any attempt to enforce the Constitution’s limits on federal power. The majority supports this conclusion by invoking, without explanation, the Necessary and Proper Clause. Regulating respondents’ conduct, however, is not “necessary and proper for carrying into Execution” Congress’ restrictions on the interstate drug trade. Art. I, §8, cl. 18. Thus, neither the Commerce Clause nor the Necessary and Proper Clause grants Congress the power to regulate respondents’ conduct.

A

As I explained at length in United States v. Lopez, 514 U. S. 549 (1995), the Commerce Clause empowers Congress to regulate the buying and selling of goods and services trafficked across state lines. Id., at 586-589 (concurring opinion). The Clause’s text, structure, and history all indicate that, at the time of the founding, the term “ ‘commerce’ consisted of selling, buying, and bartering, as well as transporting for these purposes.” Id., at 585 (Thomas, J., concurring). Commerce, or trade, stood in contrast to productive activities like manufacturing and agriculture. Id., at 586-587 (Thomas, J., concurring). Throughout founding-era dictionaries, Madison’s notes from the Constitutional Convention, The Federalist Papers, and the ratification debates, the term “commerce” is consistently used to mean trade or exchange — not all economic or gainful activity that has some attenuated connection to trade or exchange. Ibid. (Thomas, *59J., concurring); Barnett, The Original Meaning of the Commerce Clause, 68 U. Chi. L. Rev. 101, 112-125 (2001). The term “commerce” commonly meant trade or exchange (and shipping for these purposes) not simply to those involved in the drafting and ratification processes, but also to the general public. Barnett, New Evidence of the Original Meaning of the Commerce Clause, 55 Ark. L. Rev. 847, 857-862 (2003).

Even the majority does not argue that respondents’ conduct is itself “Commerce among the several States,” Art. I, § 8, el. 3. Ante, at 22. Monson and Raich neither buy nor sell the marijuana that they consume. They cultivate their cannabis entirely in the State of California — it never crosses state lines, much less as part of a commercial transaction. Certainly no evidence from the founding suggests that “commerce” included the mere possession of a good or some purely personal activity that did not involve trade or exchange for value. In the early days of the Republic, it would have been unthinkable that Congress could prohibit the local cultivation, possession, and consumption of marijuana.

On this traditional understanding of “commerce,” the Controlled Substances Act (CSA), 21 U. S. C. §801 et seq., regulates a great deal of marijuana trafficking that is interstate and commercial in character. The CSA does not, however, criminalize only the interstate buying and selling of marijuana. Instead, it bans the entire market — intrastate or interstate, noncommercial or commercial — for marijuana. Respondents are correct that the CSA exceeds Congress’ commerce power as applied to their conduct, which is purely intrastate and noncommercial.

B

More difficult, however, is whether the CSA is a valid exercise of Congress’ power to enact laws that are “necessary and proper for carrying into Execution” its power to regulate interstate commerce. Art. I, §8, cl. 18. The Necessary *60and Proper Clause is not a warrant to Congress to enact any law that bears some conceivable connection to the exercise of an enumerated power.1 Nor is it, however, a command to Congress to enact only laws that are absolutely indispensable to the exercise of an enumerated power.2

In McCulloch v. Maryland, 4 Wheat. 316 (1819), this Court, speaking through Chief Justice Marshall, set forth a test for determining when an Act of Congress is permissible under the Necessary and Proper Clause:

“Let the end be legitimate, let it be within the scope of the constitution, and all means which are appropriate, which are plainly adapted to that end, which are not prohibited, but consist with the letter and spirit of the constitution, are constitutional.” Id., at 421.

To act under the Necessary and Proper Clause, then, Congress must select a means that is “appropriate” and “plainly adapted” to executing an enumerated power; the means cannot be otherwise “prohibited” by the Constitution; and the means cannot be inconsistent with “the letter and spirit of the [Constitution.” Ibid.; D. Currie, The Constitution in the Supreme Court: The First Hundred Years 1789-1888, pp. 163-164 (1985). The CSA, as applied to respondents’ conduct, is not a valid exercise of Congress’ power under the Necessary and Proper Clause.

1

Congress has exercised its power over interstate commerce to criminalize trafficking in marijuana across state *61lines. The Government contends that banning Monson and Raich’s intrastate drug activity is “necessary and proper for carrying into Execution” its regulation of interstate drug trafficking. Art. I, § 8, cl. 18. See 21 U. S. C. §801(6). However, in order to be “necessary,” the intrastate ban must be more than “a reasonable means [of] effectuat[ing] the regulation of interstate commerce.” Brief for Petitioners 14; see ante, at 22 (majority opinion) (employing rational-basis review). It must be “plainly adapted” to regulating interstate marijuana trafficking — in other words, there must be an “obvious, simple, and direct relation” between the intrastate ban and the regulation of interstate commerce. Sabri v. United States, 541 U. S. 600, 613 (2004) (Thomas, J., concurring in judgment); see also United States v. Dewitt, 9 Wall. 41, 44 (1870) (finding ban on intrastate sale of lighting oils not “appropriate and plainly adapted means for carrying into execution” Congress’ taxing power).

On its face, a ban on the intrastate cultivation, possession, and distribution of marijuana may be plainly adapted to stopping the interstate flow of marijuana. Unregulated local growers and users could swell both the supply and the demand sides of the interstate marijuana market, making the market more difficult to regulate. Ante, at 12-13, 22 (majority opinion). But respondents do not challenge the CSA on its face. Instead, they challenge it as applied to their conduct. The question is thus whether the intrastate ban is “necessary and proper” as applied to medical marijuana users like respondents.3

Respondents are not regulable simply because they belong to a large class (local growers and users of marijuana) that *62Congress might need to reach, if they also belong to a distinct and separable subclass (local growers and users of state-authorized, medical marijuana) that does not undermine the CSA’s interstate ban. Ante, at 47-48 (O’Connor, J., dissenting). The Court of Appeals found that respondents’ “limited use is clearly distinct from the broader illicit drug market,” because “th[eir] medicinal marijuana... is not intended for, nor does it enter, the stream of commerce.” Raich v. Ashcroft, 352 F. 3d 1222, 1228 (CA9 2003). If that is generally true of individuals who grow and use marijuana for medical purposes under state law, then even assuming Congress has “obvious” and “plain” reasons why regulating intrastate cultivation and possession is necessary to regulating the interstate drug trade, none of those reasons applies to medical marijuana patients like Monson and Raich.

California’s Compassionate Use Act sets respondents’ conduct apart from other intrastate producers and users of marijuana. The Act channels marijuana use to “seriously ill Californians,” Cal. Health & Safety Code Ann. § 11362.5(b)(1)(A) (West Supp. 2005), and prohibits “the diversion of marijuana for nonmedical purposes,” § 11362.5(b)(2).4 California strictly controls the cultivation and possession of marijuana for medical purposes. To be eligible for its program, California requires that a patient have an illness that cannabis can relieve, such as cancer, AIDS, or arthritis, § 11362.5(b)(1)(A), and that he obtain a physician’s recommendation or approval, § 11362.5(d). Qualified patients must provide personal and medical information to obtain medical identification cards, and there is a statewide registry of cardholders. §§11362.715-11362.76. Moreover, the Medical Board of California has issued guidelines for physicians’ cannabis recommendations, and it sanctions physicians who do not comply with the guidelines. *63See, e. g., People v. Spark, 121 Cal. App. 4th 259, 263, 16 Cal. Rptr. 3d 840, 843 (2004).

This class of intrastate users is therefore distinguishable from others. We normally presume that States enforce their own laws, Riley v. National Federation of Blind of N. C., Inc., 487 U. S. 781, 795 (1988), and there is no reason to depart from that presumption here: Nothing suggests that California’s controls are ineffective. The scant evidence that exists suggests that few people — the vast majority of whom are aged 40 or older — register to use medical marijuana. General Accounting Office, Marijuana: Early Experiences with Four States’ Laws That Allow Use for Medical Purposes 22-23 (Rep. No. 03-189, Nov. 2002), http://www. gao.gov/new.items/d03189.pdf (all Internet materials as visited June 3, 2005, and available in Clerk of Court’s case file). In part because of the low incidence of medical marijuana use, many law enforcement officials report that the introduction of medical marijuana laws has not affected their law enforcement efforts. Id., at 32.

These controls belie the Government’s assertion that placing medical marijuana outside the CSA’s reach “would prevent effective enforcement of the interstate ban on drug trafficking.” Brief for Petitioners 33. Enforcement of the CSA can continue as it did prior to the Compassionate Use Act. Only now, a qualified patient could avoid arrest or prosecution by presenting his identification card to law enforcement officers. In the event that a qualified patient is arrested for possession or his cannabis is seized, he could seek to prove as an affirmative defense that, in conformity with state law, he possessed or cultivated small quantities of marijuana intrastate solely for personal medical use. People v. Mower, 28 Cal. 4th 457, 469-470, 49 P. 3d 1067, 1073-1075 (2002); People v. Trippet, 56 Cal. App. 4th 1532, 1549, 66 Cal. Rptr. 2d 559, 560 (1997). Moreover, under the CSA, certain drugs that present a high risk of abuse and addiction but that nevertheless have an accepted medical use — drugs like mor*64phine and amphetamines — are available by prescription. 21 U. S. C. §§ 812(b)(2)(AMB); 21 CFR § 1308.12 (2004). No one argues that permitting use of these drugs under medical supervision has undermined the CSA’s restrictions.

But even assuming that States’ controls allow some seepage of medical marijuana into the illicit drug market, there is a multibillion-dollar interstate market for marijuana. Executive Office of the President, Office of Nat. Drug Control Policy, Marijuana Fact Sheet 5 (Feb. 2004), http://www. whitehousedrugpolicy.gov/publications/factsht/marijuana/ index.html. It is difficult to see how this vast market could be affected by diverted medical cannabis, let alone in a way that makes regulating intrastate medical marijuana obviously essential to controlling the interstate drug market.

To be sure, Congress declared that state policy would disrupt federal law enforcement. It believed the across-the-board ban essential to policing interstate drug trafficking. 21 U. S. C. §801(6). But as Justice O’Connor points out, Congress presented no evidence in support of its conclusions, which are not so much findings of fact as assertions of power. Ante, at 53-55 (dissenting opinion). Congress cannot define the scope of its own power merely by declaring the necessity of its enactments.

In sum, neither in enacting the CSA nor in defending its application to respondents has the Government offered any obvious reason why banning medical marijuana use is necessary to stem the tide of interstate drug trafficking. Congress’ goal of curtailing the interstate drug trade would not plainly be thwarted if it could not apply the CSA to patients like Monson and Raich. That is, unless Congress’ aim is really to exercise police power of the sort reserved to the States in order to eliminate even the intrastate possession and use of marijuana.

2

Even assuming the CSA’s ban on locally cultivated and consumed marijuana is “necessary,” that does not mean it is *65also “proper.” The means selected by Congress to regulate interstate commerce cannot be “prohibited” by, or inconsistent with the “letter and spirit” of, the Constitution. McCulloch, 4 Wheat., at 421.

In Lopez, I argued that allowing Congress to regulate intrastate, noncommercial activity under the Commerce Clause would confer on Congress a general “police power” over the Nation. 514 U. S., at 584, 600 (concurring opinion). This is no less the case if Congress ties its power to the Necessary and Proper Clause rather than the Commerce Clause. When agents from the Drug Enforcement Administration raided Monson’s home, they seized six cannabis plants. If the Federal Government can regulate growing a half-dozen cannabis plants for personal consumption (not because it is interstate commerce, but because it is inextricably bound up with interstate commerce), then Congress’ Article I powers — as expanded by the Necessary and Proper Clause — have no meaningful limits. Whether Congress aims at the possession of drugs, guns, or any number of other items, it may continue to “appropriate] state police powers under the guise of regulating commerce.” United States v. Morrison, 529 U. S. 598, 627 (2000) (Thomas, J., concurring).

Even if Congress may regulate purely intrastate activity when essential to exercising some enumerated power, see Dewitt, 9 Wall., at 44; but see Barnett, The Original Meaning of the Necessary and Proper Clause, 6 U. Pa. J. Const. L. 183, 186 (2003) (detailing statements by Founders that the Necessary and Proper Clause was not intended to expand the scope of Congress’ enumerated powers), Congress may not use its incidental authority to subvert basic principles of federalism and dual sovereignty. Printz v. United States, 521 U. S. 898, 923-924 (1997); Alden v. Maine, 527 U. S. 706, 732-733 (1999); Garcia v. San Antonio Metropolitan Transit Authority, 469 U. S. 528, 585 (1985) (O’Connor, J., dissenting); The Federalist No. 33, pp. 204-205 (J. Cooke ed. 1961) (A. Hamilton) (hereinafter The Federalist).

*66Here, Congress has encroached on States’ traditional police powers to define the criminal law and to protect the health, safety, and welfare of their citizens.5 Brecht v. Abrahamson, 507 U. S. 619, 635 (1993); Hillsborough County v. Automated Medical Laboratories, Inc., 471 U. S. 707, 719 (1985). Further, the Government’s rationale — that it may regulate the production or possession of any commodity for which there is an interstate market — threatens to remove the remaining vestiges of States’ traditional police powers. See Brief for Petitioners 21-22; cf. Ehrlich, The Increasing Federalization of Crime, 32 Ariz. St. L. J. 825, 826, 841 (2000) (describing both the relative recency of a large percentage of federal crimes and the lack of a relationship between some of these crimes and interstate commerce). This would convert the Necessary and Proper Clause into precisely what Chief Justice Marshall did not envision, a “pretext... for the accomplishment of objects not intrusted to the government.” McCulloch, supra, at 423.

*67II

The majority advances three reasons why the CSA is a legitimate exercise of Congress’ authority under the Commerce Clause: First, respondents’ conduct, taken in the aggregate, may substantially affect interstate commerce, ante, at 22; second, regulation of respondents’ conduct is essential to regulating the interstate marijuana market, ante, at 24-25; and, third, regulation of respondents’ conduct is incidental to regulating the interstate marijuana market, ante, at 22. Justice O’Connor explains why the majority’s reasons cannot be reconciled with our recent Commerce Clause jurisprudence. The majority’s justifications, however, suffer from even more fundamental flaws.

A

. The majority holds that Congress may regulate intrastate cultivation and possession of medical marijuana under the Commerce Clause, because such conduct arguably has a substantial effect on interstate commerce. The majority’s decision is further proof that the “substantial effects” test is a “rootless and malleable standard” at odds with the constitutional design. Morrison, supra, at 627 (Thomas, J., concurring).

The majority’s treatment of the substantial effects test is rootless, because it is not tethered to either the Commerce Clause or the Necessary and Proper Clause. Under the Commerce Clause, Congress may regulate interstate commerce, not activities that substantially affect interstate commerce, any more than activities that do not fall within, but that affect, the subjects of its other Article I powers. Lopez, 514 U. S., at 589 (Thomas, J., concurring). Whatever additional latitude the Necessary and Proper Clause affords, supra, at 65-66, the question is whether Congress’ legislation is essential to the regulation of interstate commerce itself — not whether the legislation extends only to economic *68activities that substantially affect interstate commerce. Supra, at 60-61; ante, at 37 (Scalia, J., concurring in judgment).

The majority’s treatment of the substantial effects test is malleable, because the majority expands the relevant conduct. By defining the class at a high level of generality (as the intrastate manufacture and possession of marijuana), the majority overlooks that individuals authorized by state law to manufacture and possess medical marijuana exert no demonstrable effect on the interstate drug market. Supra, at 64. The majority ignores that whether a particular activity substantially affects interstate commerce — and thus comes within Congress’ reach on the majority’s approach— can turn on a number of objective factors, like state action or features of the regulated activity itself. Ante, at 47-48 (O’Connor, J., dissenting). For instance, here, if California and other States are effectively regulating medical marijuana users, then these users have little effect on the interstate drug trade.6

The substantial effects test is easily manipulated for another reason. This Court has never held that Congress can *69regulate noneconomic activity that substantially affects interstate commerce. Morrison, 529 U. S., at 613 (“[T]hus far in our Nation’s history our cases have upheld Commerce Clause regulation of intrastate activity only where that activity is economic in nature” (emphasis added)); Lopez, supra, at 560. To evade even that modest restriction on federal power, the majority defines economic activity in the broadest possible terms as “‘the production, distribution, and consumption of commodities.’”7 Ante, at 25 (quoting Webster’s Third New International Dictionary 720 (1966) (hereinafter Webster’s 3d)). This carves out a vast swath of activities that are subject to federal regulation. See ante, at 49-50 (O’Connor, J., dissenting). If the majority is to be taken seriously, the Federal Government may now regulate quilting bees, clothes drives, and potluck suppers throughout the 50 States. This makes a mockery of Madison’s assurance to the people of New York that the “powers delegated” to the Federal Government are “few and defined,” while those of the States are “numerous and indefinite.” The Federalist No. 45, at 313.

Moreover, even a Court interested more in the modern than the original understanding of the Constitution ought to resolve cases based on the meaning of words that are actually in the document. Congress is authorized to regulate “Commerce,” and respondents’ conduct does not qualify under any definition of that term.8 The majority’s opinion *70only illustrates the steady drift away from the text of the Commerce Clause. There is an inexorable expansion from “ ‘[commerce/ ” ante, at 5, to “commercial” and “economic” activity, ante, at 23, and finally to all “production, distribution, and consumption” of goods or services for which there is an “established ... interstate market,” ante, at 26. Federal power expands, but never contracts, with each new locution. The majority is not interpreting the Commerce Clause, but rewriting it.

The majority’s rewriting of the Commerce Clause seems to be rooted in the belief that, unless the Commerce Clause covers the entire web of human activity, Congress will be left powerless to regulate the national economy effectively. Ante, at 18-19; Lopez, 514 U. S., at 573-574 (Kennedy, J., concurring). The interconnectedness of economic activity is not a modern phenomenon unfamiliar to the Framers. Id., at 590-593 (Thomas, J., concurring); Letter from J. Madison to S. Roane (Sept. 2, 1819), in 3 The Founders’ Constitution 259-260 (P. Kurland & R. Lerner eds. 1987). Moreover, the Framers understood what the majority does not appear to fully appreciate: There is a danger to concentrating too much, as well as too little, power in the Federal Government. This Court has carefully avoided stripping Congress of its ability to regulate interstate commerce, but it has casually allowed the Federal Government to strip States of their ability to regulate mirastate commerce — not to mention a host of local activities, like mere drug possession, that are not commercial.

One searches the Court’s opinion in vain for any hint of what aspect of American life is reserved to the States. Yet this Court knows that “ ‘[t]he Constitution created a Federal Government of limited powers.’” New York v. United States, 505 U. S. 144, 155 (1992) (quoting Gregory v. Ashcroft, *71501 U. S. 452, 457 (1991)). That is why today’s decision will add no measure of stability to our Commerce Clause jurisprudence: This Court is willing neither to enforce limits on federal power, nor to declare the Tenth Amendment a dead letter. If stability is possible, it is only by discarding the stand-alone substantial effects test and revisiting our definition of “Commerce... among the several States.” Congress may regulate interstate commerce — not things that affect it, even when summed together, unless truly “necessary and proper” to regulating interstate commerce.

B

The majority also inconsistently contends that regulating respondents’ conduct is both incidental and essential to a comprehensive legislative scheme. Ante, at 22, 24-25. I have already explained why the CSA’s ban on local activity is not essential. Supra, at 64. However, the majority further claims that, because the CSA covers a great deal of interstate commerce, it “is of no moment” if it also “ensnares some purely intrastate activity.” Ante, at 22. So long as Congress casts its net broadly over an interstate market, according to the majority, it is free to regulate interstate and intrastate activity alike. This cannot be justified under either the Commerce Clause or the Necessary and Proper Clause. If the activity is purely intrastate, then it may not be regulated under the Commerce Clause. And if the regulation of the intrastate activity is purely incidental, then it may not be regulated under the Necessary and Proper Clause.

Nevertheless, the majority terms this the “pivotal” distinction between the present case and Lopez and Morrison. Ante, at 23. In Lopez and Morrison, the parties asserted facial challenges, claiming “that a particular statute or provision fell outside Congress’ commerce power in its entirety.” Ante, at 23. Here, by contrast, respondents claim only that the CSA falls outside Congress’ commerce power as applied *72to their individual conduct. According to the majority, while courts may set aside whole statutes or provisions, they may not “excise individual applications of a concededly valid statutory scheme.” Ibid.; see also Perez v. United States, 402 U. S. 146, 154 (1971); Maryland v. Wirtz, 392 U. S. 183, 192-193 (1968).

It is true that if respondents’ conduct is part of a “class of activities . . . and that class is within the reach of federal power,” Perez, supra, at 154 (emphasis deleted), then respondents may not point to the de minimis effect of their own personal conduct on the interstate drug market, Wirtz, supra, at 196, n. 27. Ante, at 47 (O’Connor, J., dissenting). But that begs the question at issue: whether respondents’ “class of activities” is “within the reach of federal power,” which depends in turn on whether the class is defined at a low or a high level of generality. Supra, at 61-62. If medical marijuana patients like Monson and Raich largely stand outside the interstate drug market, then courts must excise them from the CSA’s coverage. Congress expressly provided that if “a provision [of the CSA] is held invalid in one or more of its applications, the provision shall remain in effect in all its valid applications that are severable.” 21 U. S. C. § 901 (emphasis added); see also United States v. Booker, 543 U. S. 220, 320-321, and n. 9 (2005) (Thomas, J., dissenting in part).

Even in the absence of an express severability provision, it is implausible that this Court could set aside entire portions of the United States Code as outside Congress’ power in Lopez and Morrison, but it cannot engage in the more restrained practice of invalidating particular applications of the CSA that are beyond Congress’ power. This Court has regularly entertained as-applied challenges under constitutional provisions, see United States v. Raines, 362 U. S. 17, 20-21 (1960), including the Commerce Clause, see Katzenbach v. McClung, 379 U. S. 294, 295 (1964); Heart of Atlanta *73Motel, Inc. v. United States, 379 U. S. 241, 249 (1964); Wickard v. Filburn, 317 U. S. 111, 113-114 (1942), There is no reason why, when Congress exceeds the scope of its commerce power, courts may not invalidate Congress’ overreaching on a case-by-case basis. The CSA undoubtedly regulates a great deal of interstate commerce, but that is no license to regulate conduct that is neither interstate nor commercial, however minor or incidental.

If the majority is correct that Lopez and Morrison are distinct because they were facial challenges to “particular statute[s] or provision[s],” ante, at 23, then congressional power turns on the manner in which Congress packages legislation. Under the majority’s reasoning, Congress could not enact — either as a single-subject statute or as a separate provision in the CSA — a prohibition on the intrastate possession or cultivation of marijuana. Nor could it enact an intrastate ban simply to supplement existing drug regulations. However, that same prohibition is perfectly constitutional when integrated into a piece of legislation that reaches other regulable conduct. Lopez, 514 U. S., at 600-601 (Thomas, J., concurring).

Finally, the majority’s view — that because some of the CSA’s applications are constitutional, they must all be constitutional — undermines its reliance on the substantial effects test. The intrastate conduct swept within a general regulatory scheme may or may not have a substantial effect on the relevant interstate market. “[0]ne always can draw the circle broadly enough to cover an activity that, when taken in isolation, would not have substantial effects on commerce.” Id., at 600 (Thomas, J., concurring). The breadth of legislation that Congress enacts says nothing about whether the intrastate activity substantially affects interstate commerce, let alone whether it is necessary to the scheme. Because medical marijuana users in California and elsewhere are not placing substantial amounts of cannabis *74into the stream of interstate commerce, Congress may not regulate them under the substantial effects test, no matter how broadly it drafts the CSA.

* * *

The majority prevents States like California from devising drug policies that they have concluded provide much-needed respite to the seriously ill. It does so without any serious inquiry into the necessity for federal regulation or the propriety of “displacing] state regulation in areas of traditional state concern,” id., at 583 (Kennedy, J., concurring). The majority’s rush to embrace federal power “is especially unfortunate given the importance of showing respect for the sovereign States that comprise our Federal Union.” United States v. Oakland Cannabis Buyers’ Cooperative, 532 U. S. 483, 502 (2001) (Stevens, J., concurring in judgment). Our federalist system, properly understood, allows California and a growing number of other States to decide for themselves how to safeguard the health and welfare of their citizens. I would affirm the judgment of the Court of Appeals. I respectfully dissent.