Mr. Justice Stewart

delivered the opinion of the Court.

The petitioner was convicted in the District Court for the Southern District of California under an eight-count indictment charging him with transmitting wagering information by telephone from Los Angeles to Miami and Boston, in violation of a federal statute.1 At trial the Government was permitted, over the petitioner’s objection, to introduce evidence of the petitioner’s end of telephone conversations, overheard by FBI agents who had attached an electronic listening and recording device to the outside of the public telephone booth from which he had placed his calls. In affirming his conviction, the Court of Appeals rejected the contention that the recordings had been obtained in violation of the Fourth Amend*349ment, because “[tjhere was no physical entrance into the area occupied by [the petitioner].”2 We granted certiorari in order to consider the constitutional questions thus presented.3

The petitioner has phrased those questions as follows:

“A. Whether a public telephone booth is a constitutionally protected area so that evidence obtained by attaching an electronic listening recording device to the top of such a booth is obtained in violation of the right to privacy of the user of the booth.

*350“B. Whether physical penetration of a constitutionally protected area is necessary before a search and seizure can be said to be violative of the Fourth Amendment to the United States Constitution.”

We decline to adopt this formulation of the issues. In the first place, the correct solution of Fourth Amendment problems is not necessarily promoted by incantation of the phrase “constitutionally protected area.” Secondly, the Fourth Amendment cannot be translated into a general constitutional “right to privacy.” That Amendment protects individual privacy against certain kinds of governmental intrusion, but its protections go further, and often have nothing to do with privacy at all.4 Other provisions of the Constitution protect personal privacy from other forms of governmental invasion.5 But the protection of a person’s general right to privacy— his right to be let alone by other people6 — is, like the *351protection of his property and of his very life, left largely to the law of the individual States.7

Because of the misleading way the issues have been formulated, the parties have attached great significance to the characterization of the telephone booth from which the petitioner placed his calls. The petitioner has strenuously argued that the booth was a “constitutionally protected area.” The Government has maintained with equal vigor that it was not.8 But this effort to decide whether or not a given “area,” viewed in the abstract, is “constitutionally protected” deflects attention from the problem presented by this case.9 For the Fourth Amendment protects people, not places. What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection. See Lewis v. United States, 385 U. S. 206, 210; United States v. Lee, 274 U. S. 559, 563. But what he seeks-to preserve as private, even in an area accessible to the public, may be constitutionally pro*352tected. See Rios v. United States, 364 U. S. 253; Ex parte Jackson, 96 U. S. 727, 733.

The Government stresses the fact that the telephone booth from which the petitioner made his calls was constructed partly of glass, so that he was as visible after he entered it as he would have been if he had remained outside. But what he sought to exclude when he entered the booth was not the intruding eye — it was the uninvited ear. He did not shed his right to do so simply because he made his calls from a place where he might be seen. No less than an individual in a business office,10 in a friend’s apartment,11 or in a taxicab,12 a person in a telephone booth may rely upon the protection of the Fourth Amendment. One who occupies it, shuts the door behind him, and pays the toll that permits him to place a call is surely entitled to assume that the words he utters into the mouthpiece will not be broadcast to the world. To read the Constitution more narrowly is to ignore the vital role that the public telephone has come to play in private communication.

The Government contends, however, that the activities of its agents in this case should not be tested by Fourth Amendment requirements, for the surveillance technique they employed involved no physical penetration of the telephone booth from which the petitioner placed his calls. It is true that the absence of such penetration was at one time thought to foreclose further Fourth Amendment inquiry, Olmstead v. United States, 277 U. S. 438, 457, 464, 466; Goldman v. United States, 316 U. S. 129, 134-136, for that Amendment was thought to limit only searches and seizures of tangible *353property.13 But “[t]he premise that property interests control the right of the Government to search and seize has been discredited.” Warden v. Hayden, 387 U. S. 294, 304. Thus, although a closely divided Court supposed in Olmstead that surveillance without any trespass and without the seizure of any material object fell outside the ambit of the Constitution, we have since departed from the narrow view on which that decision rested. Indeed, we have expressly held that the Fourth Amendment governs not only the seizure of tangible items, but extends as well to the recording of oral statements, overheard without any “technical trespass under . . . local property law.” Silverman v. United States, 365 U. S. 505, 511. Once this much is acknowledged, and once it is recognized that the Fourth Amendment protects people— and not simply “areas” — against unreasonable searches and seizures, it becomes clear that the reach of that Amendment cannot turn upon the presence or absence of a physical intrusion into any given enclosure.

We conclude that the underpinnings of Olmstead and Goldman have been so eroded by our subsequent decisions that the “trespass” doctrine there enunciated can no longer be regarded as controlling. The Government’s activities in electronically listening to and recording the petitioner’s words violated the privacy upon which he justifiably relied while using the telephone booth and thus constituted a “search and seizure” within the meaning of the Fourth Amendment. The fact that the electronic device employed to achieve that end did not happen to penetrate the wall of the booth can have no constitutional significance.

*354The question remaining for decision, then, is whether the search and seizure conducted in this case complied with constitutional standards. In that regard, the Government’s position is that its agents acted in an entirely defensible manner: They did not begin their electronic surveillance until investigation of the petitioner’s activities had established a strong probability that he was using the telephone in question to transmit gambling information to persons in other States, in violation of federal law. Moreover, the surveillance was limited, both in scope and in duration, to the specific purpose of establishing the contents of the petitioner’s unlawful telephonic communications. The agents confined their surveillance to the brief periods during which he used the telephone booth,14 and they took great care to overhear only the conversations of the petitioner himself.15

Accepting this account of the Government’s actions as accurate, it is clear that this surveillance was so narrowly circumscribed that a duly authorized magistrate, properly notified of the need for such investigation, specifically informed of the basis on which it was to proceed, and clearly apprised of the precise intrusion it would entail, could constitutionally have authorized, with appropriate safeguards, the very limited search and seizure that the Government asserts in fact took place. Only last Term we sustained the validity of *355such an authorization, holding that, under sufficiently “precise and discriminate circumstances,” a federal court may empower government agents to employ a concealed electronic device “for the narrow and particularized purpose of ascertaining the truth of the . . . allegations” of a “detailed factual affidavit alleging the commission of a specific criminal offense.” Osborn v. United States, 385 U. S. 323, 329-330. Discussing that holding, the Court in Berger v. New York, 388 U. S. 41, said that “the order authorizing the use of the electronic device” in Osborn “afforded similar protections to those ... of conventional warrants authorizing the seizure of tangible evidence.” Through those protections, “no greater invasion of privacy was permitted than was necessary under the circumstances.” Id., at 57.16 Here, too, a similar *356judicial order could have accommodated “the legitimate needs of law enforcement” 17 by authorizing the carefully limited use of electronic surveillance.

The Government urges that, because its agents relied upon the decisions in Olmstead and Goldman, and because they did no more here than they might properly have done with prior judicial sanction, we should retroactively validate their conduct. That we cannot do. It is apparent that the agents in this case acted with restraint. Yet the inescapable fact is that this restraint was imposed by the agents themselves, not by a judicial officer. They were not required, before commencing the search, to present their estimate of probable cause for detached scrutiny by a neutral magistrate. They were not compelled, during the conduct of the search itself, to observe precise limits established in advance by a specific court order. Nor were they directed, after the search had been completed, to notify the authorizing magistrate in detail of all that had been seized. In the absence of such safeguards, this Court has never sustained a search upon the sole ground that officers reasonably expected to find evidence of a particular crime and voluntarily confined their activities to the least intrusive *357means consistent with that end. Searches conducted without warrants have been held unlawful “notwithstanding facts unquestionably showing probable cause,” Agnello v. United States, 269 U. S. 20, 33, for the Constitution requires “that the deliberate, impartial judgment of a judicial officer ... be interposed between the citizen and the police . . ..” Wong Sun v. United States, 371 U. S. 471, 481-82. “Over and again this Court has emphasized that the mandate of the [Fourth] Amendment requires adherence to judicial processes,” United States v. Jeffers, 342 U. S. 48, 51, and that searches conducted outside the judicial process, without prior approval by judge or magistrate, are per se unreasonable under the Fourth Amendment18 — subject only to a few specifically established and well-delineated exceptions.19

It is difficult to imagine how any of those exceptions could ever apply to the sort of search and seizure involved in this case. Even electronic surveillance substantially contemporaneous with an individual’s arrest could hardly be deemed an “incident” of that arrest.20 *358Nor could the use of electronic surveillance without prior authorization be justified on grounds of “hot pursuit.” 21 And, of course, the very nature of electronic surveillance precludes its use pursuant to the suspect’s consent.22

The Government does not question these basic principles. Rather, it urges the creation of a new exception to cover this case.23 It argues that surveillance of a telephone booth should be exempted from the usual requirement of advance authorization by a magistrate upon a showing of probable cause. We cannot agree. Omission of such authorization

“bypasses the safeguards provided by an objective predetermination of probable cause, and substitutes instead the far less reliable procedure of an after-the-event justification for the . . . search, too likely to be subtly influenced by the familiar shortcomings of hindsight judgment.” Beck v. Ohio, 379 U. S. 89, 96.

And bypassing a neutral predetermination of the scope of a search leaves individuals secure from Fourth Amend*359ment violations “only in the discretion of the police.” Id., at 97.

These considerations do not vanish when the search in question is transferred from the setting of a home, an office, or a hotel room to that of a telephone booth. Wherever a man may be, he is entitled to know that he will remain free from unreasonable searches and seizures. The government agents here ignored “the procedure of antecedent justification . . . that is central to the Fourth Amendment,” 24 a procedure that we hold to be a constitutional precondition of the kind of electronic surveillance involved in this case. Because the surveillance here failed to meet that condition, and because it led to the petitioner’s conviction, the judgment must be reversed.

It is so ordered.

Mr. Justice Marshall took no part in the consideration or decision of this case.

Mr. Justice Douglas,

with whom Mr. Justice Brennan joins,

concurring.

While I join the opinion of the Court, I feel compelled to reply to the separate concurring opinion of my Brother White, which I view as a wholly unwarranted green light for the Executive Branch to resort to electronic eavesdropping without a warrant in cases which the Executive Branch itself labels “national security” matters.

Neither the President nor the Attorney General is a magistrate. In matters where they believe national security may be involved they are not detached, disinterested, and neutral as a court or magistrate must be. Under the separation of powers created by the Constitution, the Executive Branch is not supposed to be neutral and disinterested. Rather it should vigorously inves*360tigate and prevent breaches of national security and prosecute those who violate the pertinent federal laws. The President and Attorney General are properly interested parties, cast in the role of adversary, in national security cases. They may even be the intended victims of subversive action. Since spies and saboteurs are as entitled to the protection of the Fourth Amendment as suspected gamblers like petitioner, I cannot agree that where spies and saboteurs are involved adequate protection of Fourth Amendment rights is assured when the President and Attorney General assume both the position of adversary- and-prosecutor and disinterested, neutral magistrate.

There is, so far as I understand constitutional history, no distinction under the Fourth Amendment between types of crimes. Article III, § 3, gives “treason” a very narrow definition and puts restrictions on its proof. But the Fourth Amendment draws no lines between various substantive offenses. The arrests in cases of “hot pursuit” and the arrests on visible or other evidence of probable cause cut across the board and are not peculiar to any kind of crime.

I would respect the present lines of distinction and not improvise because a particular crime seems particularly heinous. When the Framers took that step, as they did with treason, the worst crime of all, they made their purpose manifest.

Mr. Justice Harlan,

concurring.

I join the opinion of the Court, which I read to hold only (a) that an enclosed telephone booth is an area where, like a home, Weeks v. United States, 232 U. S. 383, and unlike a field, Hester v. United States, 265 U. S. 57, a person has a constitutionally protected reasonable expectation of privacy; (b) that electronic as well as physical intrusion into a place that is in this sense private may constitute a violation of the Fourth Amend*361ment; and (c) that the invasion of a constitutionally protected area by federal authorities is, as the Court has long held, presumptively unreasonable in the absence of a search warrant.

As the Court's opinion states, “the Fourth Amendment protects people, not places.” The question, however, is what protection it affords to those people. Generally, as here, the answer to that question requires reference to a “place.” My understanding of the rule that has emerged from prior decisions is that there is a twofold requirement, first that a person have exhibited an actual (subjective) expectation of privacy and, second, that the expectation be one that society is prepared to recognize as “reasonable.” Thus a man's home is, for most purposes, a place where he expects privacy, but objects, activities, or statements that he exposes to the “plain view” of outsiders are not “protected” because no intention to keep them to himself has been exhibited. On the other hand, conversations in the open would not be protected against being overheard, for the expectation of privacy under the circumstances would be unreasonable. Cf. Hester v. United States, supra.

The critical fact in this case is that “[o]ne who occupies it, [a telephone booth] shuts the door behind him, and pays the toll that permits him to place a call is surely entitled to assume” that his conversation is not being intercepted. Ante, at 352. The point is not that the booth is “accessible to the public” at other times, ante, at 351, but that it is a temporarily private place whose momentary occupants' expectations of freedom from intrusion are recognized as reasonable. Cf. Rios v. United States, 364 U. S. 253.

In Silverman v. United States, 365 U. S. 505, we held that eavesdropping accomplished by means of an electronic device that penetrated the premises occupied by petitioner was a violation of the Fourth Amendment. *362That case established that interception of conversations reasonably intended to be private could constitute a “search and seizure,” and that the examination or taking of physical property was not required. This view of the Fourth Amendment was followed in Wong Sun v. United States, 371 U. S. 471, at 485, and Berger v. New York, 388 U. S. 41, at 51. Also compare Osborn v. United States, 385 U. S. 323, at 327. In Silverman we found it unnecessary to re-examine Goldman v. United States, 316 U. S. 129, which had held that electronic surveillance accomplished without the physical penetration of petitioner’s premises by a tangible object did not violate the Fourth Amendment. This case requires us to reconsider Goldman, and I agree that it should now be overruled.* Its limitation on Fourth Amendment protection is, in the present day, bad physics as well as bad law, for reasonable expectations of privacy may be defeated by electronic as well as physical invasion.

Finally, I do not read the Court’s opinion to declare that no interception of a conversation one-half of which occurs in a public telephone booth can be reasonable in the absence of a warrant. As elsewhere under the Fourth Amendment, warrants are the general rule, to which the legitimate needs of law enforcement may demand specific exceptions. It will be time enough to consider any such exceptions when an appropriate occasion presents itself, and I agree with the Court that this is not one.

Mr. Justice White,

concurring.

I agree that the official surveillance of petitioner’s telephone conversations in a public booth must be sub*363jected to the test of reasonableness under the Fourth Amendment and that on the record now before us the particular surveillance undertaken was unreasonable absent a warrant properly authorizing it. This application of the Fourth Amendment need not interfere with legitimate needs of law enforcement.*

In joining the Court’s opinion, I note the Court’s acknowledgment that there are circumstances in which it is reasonable to search without a warrant. In this connection, in footnote 23 the Court points out that today’s decision does not reach national security cases. Wiretapping to protect the security of the Nation has been authorized by successive Presidents. The present Administration would apparently save national security cases from restrictions against wiretapping. See Berger v. New York, 388 U. S. 41, 112-118 (1967) (White, J., *364dissenting). We should not require the warrant procedure and the magistrate’s judgment if the President of the United States or his chief legal officer, the Attorney General, has considered the requirements of national security and authorized electronic surveillance as reasonable.

Mr. Justice Black,

dissenting.

If I could agree with the Court that eavesdropping carried on by electronic means (equivalent to wiretapping) constitutes a “search” or “seizure,” I would be happy to join the Court’s opinion. For on that premise my Brother Stewart sets out methods in accord with the Fourth Amendment to guide States in the enactment and enforcement of laws passed to regulate wiretapping by government. In this respect today’s opinion differs sharply from Berger v. New York, 388 U. S. 41, decided last Term, which held void on its face a New York statute authorizing wiretapping on warrants issued by magistrates on showings of probable cause. The Berger case also set up what appeared to be insuperable obstacles to the valid passage of such wiretapping laws by States. The Court’s opinion in this case, however, removes the doubts about state power in this field and abates to a large extent the confusion and near-paralyzing effect of the Berger holding. Notwithstanding these good efforts of the Court, I am still unable to agree with its interpretation of the Fourth Amendment.

My basic objection is twofold: (1) I do not believe that the words of the Amendment will bear the meaning given them by today’s decision, and (2) I do not believe that it is the proper role of this Court to rewrite the Amendment in order “to bring it into harmony with the times” and thus reach a result that many people believe to be desirable.

*365While I realize that an argument based on the meaning of words lacks the scope, and no doubt the appeal, of broad policy discussions and philosophical discourses on such nebulous subjects as privacy, for me the language of the Amendment is the crucial place to look in construing a written document such as our Constitution. The Fourth Amendment says that

“The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”

The first clause protects “persons, houses, papers, and effects, against unreasonable searches and seizures . . . .” These words connote the idea of tangible things with size, form, and weight, things capable of being searched, seized, or both. The second clause of the Amendment still further establishes its Framers’ purpose to limit its protection to tangible things by providing that no warrants shall issue but those “particularly describing the place to be searched, and the persons or things to be seized.” A conversation overheard by eavesdropping, whether by plain snooping or wiretapping, is not tangible and, under the normally accepted meanings of the words, can neither be searched nor seized. In addition the language of the second clause indicates that the Amendment refers not only to something tangible so it can be seized but to something already in existence so it can be described. Yet the Court’s interpretation would have the Amendment apply to overhearing future conversations which by their very nature are nonexistent until they take place. How can one “describe” a future conversation, and, if one cannot, how can a magistrate issue a warrant to eavesdrop one in the future? It is argued that information showing what *366is expected to be said is sufficient to limit the boundaries of what later can be admitted into evidence; but does such general information really meet the specific language of the Amendment which says “particularly describing” ? Rather than using language in a completely artificial way, I must conclude that the Fourth Amendment simply does not apply to eavesdropping.

Tapping telephone wires, of course, was an unknown possibility at the time the Fourth Amendment was adopted. But eavesdropping (and wiretapping is nothing more than eavesdropping by telephone) was, as even the majority opinion in Berger, supra, recognized, “an ancient practice which at common law was condemned as a nuisance. 4 Blackstone, Commentaries 168. In those days the eavesdropper listened by naked ear under the eaves of houses or their windows, or beyond their walls seeking out private discourse.” 388 U. S., at 45. There can be no doubt that the Framers were aware of this practice, and if they had desired to outlaw or restrict the use of evidence obtained by eavesdropping, I believe that they would have used the appropriate language to do so in the Fourth Amendment. They certainly would not have left such a task to the ingenuity of language-stretching judges. No one, it seems to me, can read the debates on the Bill of Rights without reaching the conclusion that its Framers and critics well knew the meaning of the words they used, what they would be understood to mean by others, their scope and their limitations. Under these circumstances it strikes me as a charge against their scholarship, their common sense and their candor to give to the Fourth Amendment’s language the eavesdropping meaning the Court imputes to it today.

I do not deny that common sense requires and that this Court often has said that the Bill of Rights’ safeguards should be given a liberal construction. This *367principle, however, does not justify construing the search and seizure amendment as applying to eavesdropping or the “seizure” of conversations. The Fourth Amendment was aimed directly at the abhorred practice of breaking in, ransacking and searching homes and other buildings and seizing people’s personal belongings without warrants'issued by magistrates. The Amendment deserves, and this Court has given it, a liberal construction in order to protect against warrantless searches of buildings and seizures of tangible personal effects. But until today this Court has refused to say that eavesdropping comes within the ambit of Fourth Amendment restrictions. See, e. g., Olmstead v. United States, 277 U. S. 438 (1928), and Goldman v. United States, 316 U. S. 129 (1942).

So far I have attempted to state why I think the words of the Fourth Amendment prevent its application to eavesdropping. It is important now to show that this has been the traditional view of the Amendment’s scope since its adoption and that the Court’s decision in this case, along with its amorphous holding in Berger last Term, marks the first real departure from that view.

The first case to reach this Court which actually involved a clear-cut test of the Fourth Amendment’s applicability to eavesdropping through a wiretap was, of course, Olmstead, su-pra. In holding that the interception of private telephone conversations by means of wiretapping was not a violation of the Fourth Amendment, this Court, speaking through Mr. Chief Justice Taft, examined the language of the Amendment and found, just as I do now, that the words could not be stretched to encompass overheard conversations:

“The Amendment itself shows that the search is to be of material things — the person, the house, his papers or his effects. The description of the warrant necessary to make the proceeding lawful, is *368that it must specify the place to be searched and the person or things to be seized. . . .

“Justice Bradley in the Boyd case [Boyd v. United States, 116 U. S. 616], and Justice Clark[e] in the Gouled case [Gouled v. United States, 255 U. S. 298], said that the Fifth Amendment and the Fourth Amendment were to be liberally construed to effect the purpose of the framers of the Constitution in the interest of liberty. But that can not justify enlargement of the language employed beyond the possible practical meaning of houses, persons, papers, and effects, or so to apply the words search and seizure as to forbid hearing or sight.” 277 U. S., at 464-465.

Goldman v. United States, 316 U. S. 129, is an even clearer example of this Court’s traditional refusal to consider eavesdropping as being covered by the Fourth Amendment. There federal agents used a detectaphone, which was placed on the wall of an adjoining room, to listen to the conversation of a defendant carried on in his private office and intended to be confined within the four walls of the room. This Court, referring to Olmstead, found no Fourth Amendment violation.

It should be noted that the Court in Olmstead based its decision squarely on the fact that wiretapping or eavesdropping does not violate the Fourth Amendment. As shown, supra, in the cited quotation from the case, the Court went to great pains to examine the actual language of the Amendment and found that the words used simply could not be stretched to cover eavesdropping. That there was no trespass was not the determinative factor, and indeed the Court in citing Hester v. United States, 265 U. S. 57, indicated that even where there was a trespass the Fourth Amendment does not automatically apply to evidence obtained by “hearing or *369sight.” The Olmstead majority characterized Hester as holding “that the testimony of two officers of the law who trespassed on the defendant’s land, concealed themselves one hundred yards away from his house and saw him come out and hand a bottle of whiskey to another, was not inadmissible. While there was a trespass, there was no search of person, house, papers or effects.” 277 U. S., at 465. Thus the clear holding of the Olmstead and Goldman cases, undiluted by any question of trespass, is that eavesdropping, in both its original and modern forms, is not violative of the Fourth Amendment.

While my reading of the Olmstead and Goldman cases convinces me that they were decided on the basis of the inapplicability of the wording of the Fourth Amendment to eavesdropping, and not on any trespass basis, this is not to say that unauthorized intrusion has not played an important role in search and seizure cases. This Court has adopted an exclusionary rule to bar evidence obtained by means of such intrusions. As I made clear in my dissenting opinion in Berger v. New York, 388 U. S. 41, 76, I continue to believe that this exclusionary rule formulated in Weeks v. United States, 232 U. S. 383, rests on the “supervisory power” of this Court over other federal courts and is not rooted in the Fourth Amendment. See Wolf v. Colorado, concurring opinion, 338 U. S. 25, 39, at 40. See also Mapp v. Ohio, concurring opinion, 367 U. S. 643, 661-666. This rule has caused the Court to refuse to accept evidence where there has been such an intrusion regardless of whether there has been a search or seizure in violation of the Fourth Amendment. As this Court said in Lopez v. United States, 373 U. S. 427, 438-439, “The Court has in the past sustained instances of 'electronic eavesdropping’ against constitutional challenge, when devices have been used to enable government agents to overhear conversations which would have been beyond the reach of the human ear [citing *370 Olmstead and Goldman]. It has been insisted only that the electronic device not be planted by an unlawful physical invasion of a constitutionally protected area. Silverman v. United States.”

To support its new interpretation of the Fourth Amendment, which in effect amounts to a rewriting of the language, the Court's opinion concludes that “the underpinnings of Olmstead and Goldman have been . . . eroded by our subsequent decisions . . . .” But the only cases cited as accomplishing this “eroding” are Silverman v. United States, 365 U. S. 505, and Warden v. Hayden, 337 U. S. 294. Neither of these cases “eroded” Olmstead or Goldman. Silverman is an interesting choice since there the Court expressly refused to re-examine the rationale of Olmstead or Goldman although such a reexamination was strenuously urged upon the Court by the petitioners’ counsel. Also it is significant that in Silverman, as the Court described it, “the eavesdropping was accomplished by means of an unauthorized physical penetration into the premises occupied by the petitioners,” 365 U. S., at 509, thus calling into play the supervisory exclusionary rule of evidence. As I have pointed out above, where there is an unauthorized intrusion, this Court has rejected admission of evidence obtained regardless of whether there has been an unconstitutional search and seizure. The majority’s decision here relies heavily on the statement in the opinion that the Court “need not pause to consider whether or not there was a technical trespass under the local property law relating to party walls.” (At 511.) Yet this statement should not becloud the fact that time and again the opinion emphasizes that there has been an unauthorized intrusion: “For a fair reading of the record in this case shows that the eavesdropping was accomplished by means of an unauthorized physical penetration into the premises occupied by the petitioners.” (At 509, emphasis added.) “Eavesdropping *371accomplished by means of such a physical intrusion is beyond the pale of even those decisions . . . (At 509, emphasis added.) “Here . . . the officers overheard the petitioners’ conversations only by usurping part of the petitioners’ house or office (At 511, emphasis added.) “[DJecision here ... is based upon the reality of an actual intrusion . . . .” (At 512, emphasis added.) “We find no occasion to re-examine Goldman here, but we decline to go beyond it, by even a fraction of an inch.” (At 512, emphasis added.) As if this were not enough, Justices Clark and Whittaker concurred with the following statement: “In view of the determination by the majority that the unauthorized physical penetration into petitioners’ premises constituted sufficient trespass to remove this case from the coverage of earlier decisions, we feel obliged to join in the Court’s opinion.” (At 513, emphasis added.) As I made clear in my dissent in Berger, the Court in Silverman held the evidence should be excluded by virtue of the exclusionary rule and “I would not have agreed with the Court’s opinion in Silverman . . . had I thought that the result depended on finding a violation of the Fourth Amendment . . . .” 383 U. S., at 79-80. In light of this and the fact that the Court expressly refused to reexamine Olmstead and Goldman, I cannot read Silver-man as overturning the interpretation stated very plainly in Olmstead and followed in Goldman that eavesdropping is not covered by the Fourth Amendment.

The other “eroding” case cited in the Court’s opinion is Warden v. Hayden, 387 U. S. 294. It appears that this case is cited for the proposition that the Fourth Amendment applies to “intangibles,” such as conversation, and the following ambiguous statement is quoted from the opinion: “The premise that property interests control the right of the Government to search and seize has been discredited.” 387 U. S., at 304. But far from being con*372cerned with eavesdropping, Warden v. Hayden upholds the seizure of clothes, certainly tangibles by any definition. The discussion of property interests was involved only with the common-law rule that the right to seize property depended upon proof of a superior property interest.

Thus, I think that although the Court attempts to convey the impression that for some reason today Olmstead and Goldman are no longer good law, it must face up to the fact that these cases have never been overruled or even “eroded.” It is the Court’s opinions in this case and Berger which for the first time since 1791, when the Fourth Amendment was adopted, have declared that eavesdropping is subject to Fourth Amendment restrictions and that conversations can be “seized.”* I must align myself with all those judges who up to this year have never been able to impute such a meaning to the words of the Amendment.

*373Since I see no way in which the words of the Fourth Amendment can be construed to apply to eavesdropping, that closes the matter for me. In interpreting the Bill of Rights, I willingly go as far as a liberal construction of the language takes me, but I simply cannot in good conscience give a meaning to words which they have never before been thought to have and which they certainly do not have in common ordinary usage. I will not distort the words of the Amendment in order to “keep the Constitution up to date” or “to bring it into harmony with the times.” It was never meant that this Court have such power, which in effect would make us a continuously functioning constitutional convention.

With this decision the Court has completed, I hope, its rewriting of the Fourth Amendment, which started only recently when the Court began referring incessantly to the Fourth Amendment not so much as a law against unreasonable searches and seizures as one to protect an individual’s privacy. By clever word juggling the Court finds it plausible to argue that language aimed specifically at searches and seizures of things that can be searched and seized may, to protect privacy, be applied to eavesdropped evidence of conversations that can neither be searched nor seized. Few things happen to an individual that do not affect his privacy in one way or another. Thus, by arbitrarily substituting the Court’s language, designed to protect privacy, for the Constitution’s language, designed to protect against unreasonable searches and seizures, the Court has made the Fourth Amendment its vehicle for holding all laws violative of the Constitution which offend the Court’s broadest concept of privacy. As I said in Griswold v. Connecticut, 381 U. S. 479, “The Court talks about a constitutional ‘right of privacy’ as though there is some constitutional provision or provisions forbidding any law ever to be passed which might abridge the ‘privacy’ *374of individuals. But there is not.” (Dissenting opinion, at 508.) I made clear in that dissent my fear of the dangers involved when this Court uses the “broad, abstract and ambiguous concept” of “privacy” as a “comprehensive substitute for the Fourth Amendment’s guarantee against 'unreasonable searches and seizures.’ ” (See generally dissenting opinion, at 507-527.)

The Fourth Amendment protects privacy only to the extent that it prohibits unreasonable searches and seizures of “persons, houses, papers, and effects.” No general right is created by the Amendment so as to give this Court the unlimited power to hold unconstitutional everything which affects privacy. Certainly the Framers, well acquainted as they were with the excesses of governmental power, did not intend to grant this Court such omnipotent lawmaking authority as that. The history of governments proves that it is dangerous to freedom to repose such powers in courts.

For these reasons I respectfully dissent.

Justice Scalia

delivered the opinion of the Court.

This case presents the question whether the use of a thermal-imaging device aimed at a private home from a public street to detect relative amounts of heat within the home constitutes a “search” within the meaning of the Fourth Amendment.

I

In 1991 Agent William Elliott of the United States Department of the Interior came to suspect that marijuana was being grown in the home belonging to petitioner Danny Kyllo, part of a triplex on Rhododendron Drive in Florence, Oregon. Indoor marijuana growth typically requires high-intensity lamps. In order to determine whether an amount of heat was emanating from petitioner’s home consistent with the use of such lamps, at 3:20 a.m. on January 16,1992, Agent Elliott and Dan Haas used an Agema Thermovision 210 thermal imager to scan the triplex. Thermal imagers detect infrared radiation, which virtually all objects emit but which is not visible to the naked eye. The imager converts radiation into images based on relative warmth — black *30is cool, white is hot, shades of gray connote relative differences; in that respect, it operates somewhat like a video camera showing heat images. The scan of Kyllo’s home took only a few minutes and was performed from the passenger seat of Agent Elliott’s vehicle across the street from the front of the house and also from the street in back of the house. The scan showed that the roof over the garage and a. side wall of petitioner’s home were relatively hot compared to the rest of the home and substantially warmer than neighboring homes in the triplex. Agent Elliott concluded that petitioner was using halide lights to grow marijuana in his house, which indeed he was. Based on tips from informants, utility bills, and the thermal imaging, a Federal Magistrate Judge issued a warrant authorizing a search of petitioner’s home, and the agents found an indoor growing operation involving more than 100 plants. Petitioner was indicted on one count of manufacturing marijuana, in violation of 21 U. S. C. § 841(a)(1). He unsuccessfully moved to suppress the evidence seized from his home and then entered a conditional guilty plea.

The Court of Appeals for the Ninth Circuit remanded the case for an evidentiary hearing regarding the intrusiveness of thermal imaging. On remand the District Court found that the Agema 210 “is a non-intrusive device which emits no rays or beams and shows a crude visual image of the heat being radiated from the outside of the house”; it “did not show any people or activity within the walls of the structure”; “[t]he device used cannot penetrate walls or windows to reveal conversations or human activities”; and “[n]o intimate details of the home were observed.” Supp. App. to Pet. for Cert. 89-40. Based on these findings, the District Court upheld the validity of the warrant that relied in part upon the thermal imaging, and reaffirmed its denial of the motion to suppress. A divided Court of Appeals initially reversed, 140 F. 3d 1249 (1998), but that *31opinion was withdrawn and the panel (after a change in composition) affirmed, 190 F. 3d 1041 (1999), with Judge Noonan dissenting. The court held that petitioner had shown no subjective expectation of privacy because he had made no attempt to conceal the heat escaping from his home, id., at 1046, and even if he had, there was no objectively reasonable expectation of privacy because the imager “did not expose any intimate details of Kyllo’s life,” only “amorphous ‘hot spots’ on the roof and exterior wall,” id., at 1047. We granted certiorari. 530 U. S. 1305 (2000).

II

The Fourth Amendment provides that [t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated.” “At the very core” of the Fourth Amendment “stands the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion.” Silverman v. United States, 365 U. S. 505, 511 (1961). With few exceptions, the question whether a warrantless search of a home is reasonable and hence constitutional must be answered no. See Illinois v. Rodriguez, 497 U. S. 177, 181 (1990); Payton v. New York, 445 U. S. 573, 586 (1980).

On the other hand, the antecedent question whether or not a Fourth Amendment “search” has occurred is not so simple under our precedent. The permissibility of ordinary visual surveillance of a home used to be clear because, well into the 20th century, our Fourth Amendment jurisprudence was tied to common-law trespass. See, e.g., Goldman v. United States, 316 U. S. 129, 134-136 (1942); Olmstead v. United States, 277 U. S. 438, 464-466 (1928). Cf. Silverman v. United States, supra, at 510-512 (technical trespass not necessary for Fourth Amendment violation; it suffices if there is “actual intrusion into a constitutionally protected area”). Visual surveillance was unquestionably lawful because “‘the *32eye cannot by the laws of England be guilty of a trespass.’ ” Boyd v. United States, 116 U. S. 616, 628 (1886) (quoting Entick v. Carrington, 19 How. St. Tr. 1029, 95 Eng. Rep. 807 (K. B. 1765)). We have since decoupled violation of a person’s Fourth Amendment rights from trespassory violation of his property, see Rakas v. Illinois, 439 U. S. 128, 143 (1978), but the lawfulness of warrantless visual surveillance of a home has still been preserved. As we observed in California v. Ciraolo, 476 U. S. 207, 213 (1986), “[t]he Fourth Amendment protection of the home has never been extended to require law enforcement officers to shield their eyes when passing by a home on public thoroughfares.”

One might think that the new validating rationale would be that examining the portion of a house that is in plain public view, while it is a “search”1 despite the absence of trespass, is not an “unreasonable” one under the Fourth Amendment. See Minnesota v. Carter, 525 U. S. 83, 104 (1998) (Breyer, J., concurring in judgment). But in fact we have held that visual observation is no “search” at all— perhaps in order to preserve somewhat more intact our doctrine that warrantless searches are presumptively unconstitutional. See Dow Chemical Co. v. United States, 476 U. S. 227, 234-235, 239 (1986). In assessing when a search is not a search, we have applied somewhat in reverse the principle first enunciated in Katz v. United States, 389 U. S. 347 (1967). Katz involved eavesdropping by means of an electronic listening device placed on the outside of a telephone booth — a location not within the catalog (“persons, houses, papers, and effects”) that the Fourth Amendment protects against unreasonable searches. We held that the *33Fourth Amendment nonetheless protected Katz from the warrantless eavesdropping because he “justifiably relied” upon the privacy of the telephone booth. Id., at 353. As Justice Harlan’s oft-quoted concurrence described it, a Fourth Amendment search occurs when the government violates a subjective expectation of privacy that society recognizes as reasonable. See id., at 361. We have subsequently applied this principle to hold that a Fourth Amendment search does not occur — even when the explicitly protected location of a house is concerned — unless “the individual manifested a subjective expectation of privacy in the object of the challenged search,” and “society [is] willing to recognize that expectation as reasonable.” Ciraolo, supra, at 211. We have applied this test in holding that it is not a search for the police to use a pen register at the phone company to determine what numbers were dialed in a private home, Smith v. Maryland, 442 U. S. 735, 743-744 (1979), and we have applied the test on two different occasions in holding that aerial surveillance of private homes and surrounding areas does not constitute a search, Ciraolo, supra; Florida, v. Riley, 488 U. S. 445 (1989).

The present case involves officers on a public street engaged in more than naked-eye surveillance of a home. We have previously reserved judgment as to how much technological enhancement of ordinary perception from such a vantage point, if any, is too much. While we upheld enhanced aerial photography of an industrial complex in Dow Chemical, we noted that we found “it important that this is not an area immediately adjacent to a private home, where privacy expectations are most heightened,” 476 U. S., at 237, n. 4 (emphasis in original).

III

It would be foolish to contend that the degree of privacy secured to citizens by the Fourth Amendment has been *34entirely unaffected by the advance of technology. For example, as the cases discussed above make clear, the technology enabling human flight has exposed to public view (and hence, we have said, to official observation) uncovered portions of the house and its curtilage that once were private. See Ciraolo, supra, at 215. The question we confront today is what limits there are upon this power of technology to shrink the realm of guaranteed privacy.

The Katz test — whether the individual has an expectation of privacy that society is prepared to recognize as reasonable — has often been criticized as circular, and hence subjective and unpredictable. See 1 W. LaFave, Search and Seizure § 2.1(d), pp. 393-394 (3d ed. 1996); Posner, The Uncertain Protection of Privacy by the Supreme Court, 1979 S. Ct. Rev. 173, 188; Carter, supra, at 97 (Scalia, J., concurring). But see Rakas, supra, at 143-144, n. 12. While it may be difficult to refine Katz when the search of areas such as telephone booths, automobiles, or even the eurtilage and uncovered portions of residences is at issue, in the case of the search of the interior of homes — the prototypical and hence most commonly litigated area of protected privacy— there is a ready criterion, with roots deep in the common law, of the minimal expectation of privacy that exists, and that is acknowledged to be reasonable. To withdraw protection of this minimum expectation would be to permit police technology to erode the privacy guaranteed by the Fourth Amendment. We think that obtaining by sense-enhancing technology any information regarding the interior of the home that could not otherwise have been obtained without physical “intrusion into a constitutionally protected area,” Silverman, 365 U. S., at 512, constitutes a search— at least where (as here) the technology in question is not in general public use. This assures preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted. On the basis of this criterion, the *35information obtained by the thermal imager in this ease was the product of a search.2

The Government maintains, however, that the thermal imaging must be upheld because it detected “only heat radiating from the external surface of the house,” Brief for United States 26. The dissent makes this its leading point, see post, at 41, contending that there is a fundamental difference between what it calls “off-the-wall” observations and “through-the-wall surveillance.” But just as a thermal imager captures only heat emanating from a house, so also a powerful directional microphone picks up only sound emanating from a house — and a satellite capable of scanning from many miles away would pick up only visible light emanating from a house. We rejected such a mechanical interpretation of the Fourth Amendment in Katz, where the eavesdropping device picked up only sound waves that reached the exterior of the phone booth. Reversing that approach would leave the homeowner at the mercy of advancing technology— including imaging technology that could discern all human *36activity in the home. While the technology used in the present case was relatively crude, the rule we adopt must take account of more sophisticated systems that are already in use or in development.3 The dissent’s reliance on the distinction between “off-the-wall” and “through-the-wall” observation is entirely incompatible with the dissent’s belief, which we discuss below, that thermal-imaging observations of the intimate details of a home are impermissible. The most sophisticated thermal-imaging devices continue to measure heat “off-the-wall” rather than “through-the-wall”; the dissent’s disapproval of those more sophisticated thermal-imaging devices, see post, at 49, is an acknowledgment that there is no substance to this distinction. As for the dissent’s extraordinary assertion that anything learned through “an inference” cannot be a search, see post, at 44, that would validate even the “through-the-wall” technologies that the dissent purports to disapprove. Surely the dissent does not believe that the through-the-wall radar or ultrasound technology produces an 8-by-10 Kodak glossy that needs no analysis (i. e., the making of inferences). And, of course, the novel proposition that inference insulates a search is blatantly contrary to United States v. Karo, 468 U. S. 705 (1984), where the police “inferred” from the activation of a beeper that a certain can of ether was in the home. The police ac*37tivity was held to be a search, and the search was held unlawful.4

The Government also contends that the thermal imaging was constitutional because it did not “detect private activities occurring in private areas,” Brief for United States 22. It points out that in Dow Chemical we observed that the enhanced aerial photography did not reveal any “intimate details.” 476 U. S., at 238. Dow Chemical, however, involved enhanced aerial photography of an industrial complex, which does not share the Fourth Amendment sanctity of the home. The Fourth Amendment’s protection of the home has never been tied to measurement of the quality or quantity of information obtained. In Silverman, for example, we made clear that any physical invasion of the structure of the home, “by even a fraction of an inch,” was too much, 365 U. S., at 512, and there is certainly no exception to the warrant requirement for the officer who barely cracks open the front door and sees nothing but the non-intimate rug on the vestibule floor. In the home, our cases show, all details are intimate details, because the entire area is held safe from prying government eyes. Thus, in Karo, supra, the only thing detected was a can of ether in the *38home; and in Arizona v. Hicks, 480 U. S. 321 (1987), the only thing detected by a physical search that went beyond what officers lawfully present could observe in “plain view” was; the registration number of a phonograph turntable. These were intimate details because they were details of the home, just as was the detail of how warm — or even how relatively warm — Kyllo was heating his residence.5

Limiting the prohibition of thermal imaging to “intimate details” would not only be wrong in principle; it would be impractical in application, failing to provide “a workable accommodation between the needs of law enforcement and the interests protected by the Fourth Amendment,” Oliver v. United States, 466 U. S. 170, 181 (1984). To begin with, there is no necessary connection between the sophistication of the surveillance equipment and the “intimacy” of the details that it observes — which means that one cannot say (and the police cannot be assured) that use of the relatively crude equipment at issue here will always be lawful. The Agema Thermovision 210 might disclose, for example, at what hour each night the lady of the house takes her daily sauna and bath — a detáil that many would consider “intimate”; and a much more sophisticated system might detect nothing more intimate than the fact that someone left a closet light on. We could not, in other words, develop a rule approving only that through-the-wall surveillance which identifies objects no smaller than 36 by 36 inches, but would have to develop a jurisprudence specifying which *39home activities are “intimate” and which are not. And even when (if ever) that jurisprudence were fully developed, no police officer would be able to know in advance whether his through-the-wall surveillance picks up “intimate” details— and thus would be unable to know in advance whether it is constitutional.

The dissent’s proposed standard — whether the technology offers the “functional equivalent of actual presence in the area being searched,” post, at 47 — would seem quite similar to our own at first blush. The dissent concludes that Katz was such a case, but then inexplicably asserts that if the same listening device only revealed the volume of the conversation, the surveillance would be permissible, post, at 49-50. Yet if, without technology, the police could not discern volume without being actually present in the phone booth, Justice Stevens should conclude a search has occurred. Cf. Karo, 468 U. S., at 735 (Stevens, J., concurring in part and dissenting in part) (“I find little comfort in the Court’s notion that no invasion of privacy occurs until a listener obtains some significant information by use of the device. ... A bathtub is a less private area when the plumber is present even if his back is turned”). The same should hold for the interior heat of the home if only a person present in the home could discern the heat. Thus the driving force of the dissent, despite its recitation of the above standard, appears to be a distinction among different types of information — whether the “homeowner would even care if anybody noticed,” post, at 50. The dissent offers no practical guidance for the application of this standard, and for reasons already discussed, we believe there can be none. The people in their houses, as well as the police, deserve more precision.6

*40We have said that the Fourth Amendment draws “a firm line at the entrance to the house,” Payton, 445 U. S., at 590. That line, we think, must be not only firm but also bright— which requires clear specification of those methods of surveillance that require a warrant. While it is certainly possible to conclude from the videotape of the thermal imaging that occurred in this case that no “significant” compromise of the homeowner’s privacy has occurred, we must take the long view, from the original meaning of the Fourth Amendment forward.

“The Fourth Amendment is to be construed in the light of what was deemed an unreasonable search and seizure when it was adopted, and in a manner which will conserve public interests as well as the interests and rights of individual citizens.” Carroll v. United States, 267 U. S. 132, 149 (1925).

Where, as here, the Government uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a “search” and is presumptively unreasonable without a warrant.

Since we hold the Thermovision imaging to have been an unlawful search, it will remain for the District Court to determine whether, without the evidence it provided, the search warrant issued in this case was supported by probable cause — and if not, whether there is any other basis for supporting admission of the evidence that the search pursuant to the warrant produced.

*41* * *

The judgment of the Court of Appeals is reversed; the case is remanded for further proceedings consistent with this opinion.

It is so ordered.

Justice Stevens,

with whom The Chief Justice, Justice O’Connor, and Justice Kennedy join, dissenting.

There is, in my judgment, a distinction of constitutional magnitude between “ through-the-wall surveillance” that gives the observer or listener direct access to information in a private area, on the one hand, and the thought processes used to draw inferences from information in the public domain, on the other hand. The Court has crafted a rule that purports to deal with direct observations of the inside of the home, but the case before us merely involves indirect deductions from “off-the-wall” surveillance, that is, observations of the exterior of the home. Those observations were made with a fairly primitive thermal imager that gathered data exposed on the outside of petitioner’s home but did not invade any constitutionally protected interest in privacy.1 Moreover, I believe that the supposedly “bright-line” rule the Court has created in response to its concerns about future technological developments is unnecessary, unwise, and inconsistent with the Fourth Amendment.

There is no need for the Court to craft a new rule to decide this case, as it is controlled by established principles from *42our Fourth Amendment jurisprudence. One of those core principles, of course, is that “searches and seizures inside a home without a warrant are presumptively unreasonable.”1 Payton v. New York, 445 U. S. 573, 586 (1980) (emphasis added). But it is equally well settled that searches and seizures of property in plain view are presumptively reasonable. See id., at 586-587.2 Whether that property is residential or commercial, the basic principle is the same: ‘“What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection.’ ” California v. Ciraolo, 476 U. S. 207, 213 (1986) (quoting Katz v. United States, 389 U. S. 347, 351 (1967)); see Florida v. Riley, 488 U. S. 445, 449-450 (1989); California v. Greenwood, 486 U. S. 35, 40-41 (1988); Dow Chemical Co. v. United States, 476 U. S. 227, 235-236 (1986); Air Pollution Variance Bd. of Colo. v. Western Alfalfa Cory., 416 U. S. 861, 865 (1974). That is the principle implicated here.

While the Court “take[s] the long view” and decides this case based largely on the potential of yet-to-be-developed technology that might allow “through-the-wall surveillance,” ante, at 38-40; see ante, at 36, n. 3, this case involves nothing more than off-the-wall surveillance by law enforcement officers to gather information exposed to the general public from the outside of petitioner’s home. All that the infrared camera did in this case was passively measure heat emitted *43from the exterior surfaces of petitioner’s home; all that those measurements showed were relative differences in emission levels, vaguely indicating that some areas of the roof and outside walls were warmer than others. As still images from the infrared scans show, see Appendix, infra, no details regarding the interior of petitioner’s home were revealed. Unlike an x-ray scan, or other possible “through-the-wall” techniques, the detection of infrared radiation emanating from the home did not accomplish “an unauthorized physical penetration into the premises,” Silverman v. United States, 365 U. S. 505, 509 (1961), nor did it “obtain information that it could not have obtained by observation from outside the curtilage of the house,” United States v. Karo, 468 U. S. 705, 715 (1984).

Indeed, the ordinary use of the senses might enable a neighbor or passerby to notice the heat emanating from a building, particularly if it is vented, as was the case here. Additionally, any member of the public might notice that one part of a house is warmer than another part or a nearby building if, for example, rainwater evaporates or snow melts at different rates across its surfaces. Such use of the senses would not convert into an unreasonable search if, instead, an adjoining neighbor allowed an officer onto her property to verify her perceptions with a sensitive thermometer. Nor, in my view, does such observation become an unreasonable search if made from a distance with the aid of a device that merely discloses that the exterior of one house, or one area of the house, is much warmer than another. Nothing more occurred in this case.

Thus, the notion that heat emissions from the outside of a dwelling are a private matter implicating the protections of the Fourth Amendment (the text of which guarantees the right of people “to be secure in their ... houses” against unreasonable searches and seizures (emphasis added)) is not only unprecedented but also quite difficult to take seriously. Heat waves, like aromas that are generated in a kitchen, or *44in a laboratory or opium den, enter the public domain if and when they leave a building. A subjective expectation that they would remain private is not only implausible but also surely not “one that society is prepared to recognize as ‘reasonable.’ ” Katz, 389 U. S., at 361 (Harlan, J., concurring).

To be sure, the homeowner has a reasonable expectation of privacy concerning what takes place within the home, and the Fourth Amendment’s protection against physical invasions of the home should apply to their functional equivalent. But the equipment in this case did not penetrate the walls of petitioner’s home, and while it did pick up “details of the home” that were exposed to the public, ante, at 38, it did not obtain “any information regarding the interior of the home,” ante, at 34 (emphasis added). In the Court’s own words, based on what the thermal imager “showed” regarding the outside of petitioner’s home, the officers “concluded” that petitioner was engaging in illegal activity inside the home. Ante, at 30. It would be quite absurd to characterize their thought processes as “searches,” regardless of whether they inferred (rightly) that petitioner was growing marijuana in his house, or (wrongly) that “the lady of the house [was taking] her daily sauna and bath.” Ante, at 38. In either case, the only conclusions the officers reached concerning the interior of the home were at least as indirect as those that might have been inferred from the contents of discarded garbage, see California v. Greenwood, 486 U. S. 35 (1988), or pen register data, see Smith v. Maryland, 442 U. S. 735 (1979), or, as in this case, subpoenaed utility records, see 190 F. 3d 1041, 1043 (CA9 1999). For the first time in its history, the Court assumes that an inference can amount to a Fourth Amendment violation. See ante, at 36-37.3

*45Notwithstanding the implications of today’s decision, there is a strong public interest in avoiding constitutional litigation over the monitoring of emissions from homes, and over the inferences drawn from such monitoring. Just as “the police cannot reasonably be expected to avert their eyes from evidence of criminal activity that could have been observed by any member of the public,” Greenwood, 486 U. S., at 41, so too public officials should not have to avert their senses or their equipment from detecting emissions in the public domain such as excessive heat, traces of smoke, suspicious odors, odorless gases, airborne particulates, or radioactive emissions, any of which could identify hazards to the community. In my judgment, monitoring such emissions with “sense-enhancing technology,” ante, at 34, and drawing useful conclusions from such monitoring, is an entirely reasonable public service.

On the other hand, the countervailing privacy interest is at best trivial. After all, homes generally are insulated to keep heát in, rather than to prevent the detection of heat going out, and it does not seem to me that society will suffer from a rule requiring the rare homeowner who both intends to engage in uncommon activities that produce extraordinary amounts of heat, and wishes to conceal that production from outsiders, to make sure that the surrounding area is well insulated. Cf. United States v. Jacobsen, 466 U. S. 109, 122 (1984) (“The concept of an interest in privacy that society is prepared to recognize as reasonable is, by its very nature, critically different from the mere expectation, however well *46justified, that certain facts will not come to the attention of the authorities”). The interest in concealing the heat escaping from one’s house pales in significance to “the chief evil against which the wording of the Fourth Amendment is directed,” the “physical entry of the home,” United States v. United States Dist. Court for Eastern Dist. of Mich., 407 U. S. 297, 313 (1972), and it is hard to believe that it is an interest the Framers sought to protect in our Constitution.

Since what was involved in this case was nothing more than drawing inferences from off-the-wall surveillance, rather than any “through-the-wall” surveillance, the officers’ conduct did not amount to a search and was perfectly reasonable.4

II

Instead of trying to answer the question whether the use of the thermal imager in this case was even arguably unreasonable, the Court has fashioned a rule that is intended to provide essential guidance for the day when “more sophisticated systems” gain the “ability to 'see’ through walls and other opaque barriers.” Ante, at 36, and n. 3. The newly minted rule encompasses “obtaining [1] by sense-enhancing technology [2] any information regarding the interior of the home [3] that could not otherwise have been obtained without physical intrusion into a constitutionally protected area ... [4] at least where (as here) the technology in question is not in general public use.” Ante, at 34 (internal quotation marks omitted). In my judgment, the *47Court’s new rule is at once too broad and too narrow, and is not justified by the Court’s explanation for its adoption. As I have suggested, I would not erect a constitutional impediment to the use of sense-enhancing technology unless it provides its user with the functional equivalent of actual presence in the area being searched.

Despite the Court’s attempt to draw a line that is “not only firm but also bright,” ante, at 40, the contours of its new rule are uncertain because its protection apparently dissipates as soon as the relevant technology is “in general public use,” ante, at 34. Yet how much use is general public use is not even hinted at by the Court’s opinion, which makes the somewhat doubtful assumption that the thermal imager used in this .case does not satisfy that criterion.5 In any event, putting aside its lack of clarity, this criterion is somewhat perverse because it seems likely that the threat to privacy will grow, rather than recede, as the use of intrusive equipment becomes more readily available.

It is clear, however, that the category of “sense-enhancing technology” covered by the new rule, ibid., is far too broad. It would, for example, embrace potential mechanical substitutes for dogs trained to react when they sniff narcotics. But in United States v. Place, 462 U. S. 696, 707 (1983), we held that a dog sniff that “discloses only the presence or absence of narcotics” does “not constitute a ‘search’ within the meaning of the Fourth Amendment,” and it must follow that sense-enhancing equipment that identifies nothing but illegal *48activity is not a search either. Nevertheless, the use of such a device would be unconstitutional under the Court’s rule, as would the use of other new devices that might detect the odor of deadly bacteria or chemicals for making a new type of high explosive, even if the devices (like the dog sniffs) are “so limited both in the manner in which” they obtain information and “in the content of the information” they reveal. Ibid. If nothing more than that sort of information could be obtained by using the devices in a public place to monitor emissions from a house, then their use would be no more objectionable than the use of the thermal imager in this case.

The application of the Court’s new rule to “any information regarding the interior of the home,” ante, at 34, is also unnecessarily broad. If it takes sensitive equipment to detect an odor that identifies criminal conduct and nothing else, the fact that the odor emanates from the interior of a home should not provide it with constitutional protection. See supra, at 47 and this page. The criterion, moreover, is too sweeping in that information “regarding” the interior of a home apparently is not just information obtained through its walls, but also information concerning the outside of the building that could lead to (however many) inferences “regarding” what might be inside. Under that expansive view, I suppose, an officer using an infrared camera to observe a man silently entering the side door of a house at night carrying a pizza might conclude that its interior is now occupied by someone who likes pizza, and by doing so the officer would be guilty of conducting an unconstitutional “search” of the home.

Because the new rule applies to information regarding the “interior” of the home, it is too narrow as well as too broad. Clearly, a rule that is designed to protect individuals from the overly intrusive use of sense-enhancing equipment should not be limited to a home. If such equipment *49did provide its user with the functional equivalent of access to a private place — such as, for example, the telephone booth involved in Katz, or an office building — then the rule should apply to such an area as well as to a home. See Katz, 389 U. S., at 351 (“[T]he Fourth Amendment protects people, not places”).

The final requirement of the Court’s new, rule, that the information “could not otherwise have been obtained without physical intrusion into a constitutionally protected area,” ante, at 34 (internal quotation marks omitted), also extends too far as the Court applies it. As noted, the Court effectively treats the mental process of analyzing data obtained from external sources as the equivalent of a physical intrusion into the home. See supra, at 44. As I have explained, however, the process of drawing inferences from data in the public domain should not be characterized as a search.

The two reasons advanced by the Court as justifications for the adoption of its new rule are both unpersuasive. First, the Court suggests that its rule is compelled by our holding in Katz, because in that case, as in this, the surveillance consisted of nothing more than the monitoring of waves emanating from a private area into the public domain. See ante, at 35. Yet there are critical differences between the cases. In Katz, the electronic listening device attached to the outside of the phone booth allowed the officers to pick up the content of the conversation inside the booth, making them the functional equivalent of intruders because they gathered information that was otherwise available only to someone inside the private area; it would be as if, in this case, the thermal imager presented a view of the heat-generating activity inside petitioner’s home. By contrast, the thermal imager here disclosed only the relative amounts of heat radiating from the house; it would be as if, in Katz, the listening device disclosed only the rela*50tive volume of sound leaving the booth, which presumably was discernible in the public domain.6 Surely, there is a significant difference between the general and well-settled expectation that strangers will not have direct access to the contents of private communications, on the one hand, and the rather theoretical expectation that an occasional homeowner would even care if anybody noticed the relative amounts of heat emanating from the walls of his house, on the other. It is pure hyperbole for the Court to suggest that refusing to extend the holding of Katz to this case would leave the homeowner at the mercy of “technology that could discern all human activity in the home.” Ante, at 35-36.

Second, the Court argues that the permissibility of “through-the-wall surveillance” cannot depend on a distinction between observing “intimate details” such as “the lady of the house [taking] her daily sauna and bath,” and noticing only “the nonintimate rug on the vestibule floor” or “objects no smaller than 36 by 36 inches.” Ante, at 37, 38-39. This entire argument assumes, of course, that the thermal imager in this case could or did perform “through-the-wall surveillance” that could identify any detail “that would previously have been unknowable without physical intrusion.” Ante, at 39-40. In fact, the device could not, see n. 1, supra, and did not, see Appendix, infra, enable its user to identify either the lady of the house, the rug on the vestibule floor, or anything else inside the house, whether smaller or larger than 36 by 36 inches. Indeed, the vague thermal images of petitioner’s home that are reproduced in the Appendix were submitted by him to the District Court as part of an expert report raising the question whether the device could even take “accurate, consistent infrared images” of the *51 outside of his house. Defendant’s Exh. 107, p. 4. But even if the device could reliably show extraordinary differences in the amounts of heat leaving his home, drawing the inference that there was something suspicious occurring inside the residence — a conclusion that officers far less gifted than Sherlock Holmes would readily draw — does not qualify as “through-the-wall surveillance,” much less a Fourth Amendment violation.

Ill

Although the Court is properly and commendably concerned about the threats to privacy that may flow from advances in the technology available to the law enforcement profession, it has unfortunately failed to heed the tried and true counsel of judicial restraint. Instead of concentrating on the rather mundane issue that is actually presented by the case before it, the Court has endeavored to craft an all-encompassing rule for the future. It would be far wiser to give legislators an unimpeded opportunity to grapple with these emerging issues rather than to shackle them with prematurely devised constitutional constraints.

I respectfully dissent.

[Appendix to opinion of Stevens, J., follows this page.]

*52APPENDIX TO OPINION OF STEVENS, J.

(Images and text reproduced from defendant’s exhibit 107)

Top left: Infrared image of a video frame from the videotape submitted as evidence in this case. The thermogram indicates the suspect house as it appeared with the Gain and contrast in its default setting. Only the outline of the house is visible. The camera used was the Thermovision 210.

•Top Right: Infrared image of a subsequent videoframe taken from the videotape. The gain and contrast settings have been increased in order to make the walls and roof of the structure appear hotter than what it actually is.

Bottom Left: Infrared image of the opposite side of the suspects house. The thermogram is also taken from the same videotape. The camera settings are in the default mode and the outline of the house is barely visible. Only the hot electrical transformer and the street light are identifiable. Bottom Right: The same image, but with the gain and contrast increased. This change in camera settings cause any object to appear hotter than what it actually is. The arrow indicates the overloading of an area immediately around a hot object in this case the electrical transformer and the streetlight. This overloading of the image is an inherent design flaw in the camera itself.

*402Justice Scalia

delivered the opinion of the Court.

We decide whether the attachment of a Global-Positioning-System (GPS) tracking device to an individual’s vehicle, and subsequent use of that device to monitor the vehicle’s movements on public streets, constitutes a search or seizure within the meaning of the Fourth Amendment.

HH

In 2004 respondent Antoine Jones, owner and operator of a nightclub in the District of Columbia, came under suspicion of trafficking in narcotics and was made the target of an investigation by a joint Federal Bureau of Investigation and Metropolitan Police Department task force. Officers employed various investigative techniques, including visual surveillance of the nightclub, installation of a camera focused on the front door of the club, and a pen register and wiretap covering Jones’s cellular phone.

Based in part on information gathered from these sources, in 2005 the Government applied to the United States District Court for the District of Columbia for a warrant authorizing the use of an electronic tracking device on the Jeep Grand Cherokee registered to Jones’s wife. A warrant issued, au*403thorizing installation of the device in the District of Columbia and within 10 days.

On the 11th day, and not in the District of Columbia but in Maryland,1 agents installed a GPS tracking device on the undercarriage of the Jeep while it was parked in a public parking lot. Over the next 28 days, the Government used the device to track the vehicle’s movements, and once had to replace the device’s battery when the vehicle was parked in a different public lot in Maryland. By means of signals from multiple satellites, the device established the vehicle’s location within 50 to 100 feet, and communicated that location by cellular phone to a Government computer. It relayed more than 2,000 pages of data over the 4-week period.

The Government ultimately obtained a multiple-count indictment charging Jones and several alleged co-conspirators with, as relevant here, conspiracy to distribute and possess with intent to distribute five kilograms or more of cocaine and 50 grams or more of cocaine base, in violation of 21 U. S. C. §§ 841 and 846. Before trial, Jones filed a motion to suppress evidence obtained through the GPS device. The District Court granted the motion only in part, suppressing the data obtained while the vehicle was parked in the garage adjoining Jones’s residence. 451 F. Supp. 2d 71, 88 (2006). It held the remaining data admissible, because “ ‘[a] person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another.’ ” Ibid, (quoting United States v. Knotts, 460 U. S. 276, 281 (1983)). Jones’s trial in October 2006 produced a hung jury on the conspiracy count.

In March 2007, a grand jury returned another indictment, charging Jones and others with the same conspiracy. The Government introduced at trial the same GPS-derived locational data admitted in the first trial, which connected Jones *404to the alleged conspirators’ stash house that contained $850,000 in cash, 97 kilograms of cocaine, and 1 kilogram of cocaine base. The jury returned a guilty verdict, and the District Court sentenced Jones to life imprisonment. The United States Court of Appeals for the District of Columbia Circuit reversed the conviction because of admission of the evidence obtained by warrantless use of the GPS device which, it said, violated the Fourth Amendment. United States v. Maynard, 615 F. 3d 544 (2010). The D. C. Circuit denied the Government’s petition for rehearing en banc, with four judges dissenting. 625 F. 3d 766 (2010). We granted certiorari, 564 U. S. 1036 (2011).

1 — 1 1 — I

A

The Fourth Amendment provides in relevant part that “[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated.” It is beyond dispute that a vehicle is an “effect” as that term is used in the Amendment. United States v. Chadwick, 433 U. S. 1, 12 (1977). We hold that the Government’s installation of a GPS device on a target’s vehicle,2 and its use of that device to monitor the vehicle’s movements, constitutes a “search.”

It is important to be clear about what occurred in this case: The Government physically occupied private property for the purpose of obtaining information. We have no doubt that such a physical intrusion would have been considered a *405“search” within the meaning of the Fourth Amendment when it was adopted. Entick v. Carrington, 95 Eng. Rep. 807 (C. P. 1765), is a “case we have described as a ‘monument of English freedom’ ‘undoubtedly familiar’ to ‘every American statesman’ at the time the Constitution was adopted, and considered to be ‘the true and ultimate expression of constitutional law’ ” with regard to search and seizure. Brower v. County of Inyo, 489 U. S. 593, 596 (1989) (quoting Boyd v. United States, 116 U. S. 616, 626 (1886)). In that case, Lord Camden expressed in plain terms the significance of property rights in search-and-seizure analysis:

“[O]ur law holds the property of every man so sacred, that no man can set his foot upon his neighbour’s close without his leave; if he does he is a trespasser, though he does no damage at all; if he will tread upon his neigh-bour’s ground, he must justify it by law.” Entick, swpra, at 817.

The text of the Fourth Amendment reflects its close connection to property, since otherwise it would have referred simply to “the right of the people to be secure against unreasonable searches and seizures”; the phrase “in their persons, houses, papers, and effects” would have been superfluous.

Consistent with this understanding, our Fourth Amendment jurisprudence was tied to common-law trespass, at least until the latter half of the 20th century. Kyllo v. United States, 533 U. S. 27, 31 (2001); Kerr, The Fourth Amendment and New Technologies: Constitutional Myths and the Case for Caution, 102 Mich. L. Rev. 801, 816 (2004). Thus, in Olmstead v. United States, 277 U. S. 438 (1928), we held that wiretaps attached to telephone wires on the public streets did not constitute a Fourth Amendment search because “ft]here was no entry of the houses or offices of the defendants,” id., at 464.

Our later cases, of course, have deviated from that exclusively property-based approach. In Katz v. United States, *406389 U. S. 347, 351 (1967), we said that “the Fourth Amendment protects people, not places,” and found a violation in attachment of an eavesdropping device to a public telephone booth. Our later cases have applied the analysis of Justice Harlan’s concurrence in that case, which said that a violation occurs when government officers violate a person’s “reasonable expectation of privacy,” id., at 360. See, e. g., Bond v. United States, 529 U. S. 334 (2000); California v. Ciraolo, 476 U. S. 207 (1986); Smith v. Maryland, 442 U. S. 735 (1979).

The Government contends that the Harlan standard shows that no search occurred here, since Jones had no “reasonable expectation of privacy” in the area of the Jeep accessed by Government agents (its underbody) and in the locations of the Jeep on the public roads, which were visible to all. But we need not address the Government’s contentions, because Jones’s Fourth Amendment rights do not rise or fall with the Katz formulation. At bottom, we must “assur[e] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted.” Kyllo, supra, at 34. As explained, for most of our history the Fourth Amendment was understood to embody a particular concern for government trespass upon the areas (“persons, houses, papers, and effects”) it enumerates.3 Katz did not *407repudiate that understanding. Less than two years later the Court upheld defendants’ contention that the Government could not introduce against them conversations between other people obtained by warrantless placement of electronic surveillance devices in their homes. The opinion rejected the dissent’s contention that there was no Fourth Amendment violation “unless the conversational privacy of the homeowner himself is invaded.”4 Alderman v. United States, 394 U. S. 165, 176 (1969). “[W]e [do not] believe that Katz, by holding that the Fourth Amendment protects persons and their private conversations, was intended to withdraw any of the protection which the Amendment extends to the home .. . .” Id., at 180.

More recently, in Soldal v. Cook County, 506 U. S. 56 (1992), the Court unanimously rejected the argument that although a “seizure” had occurred “in a ‘technical’ sense” when a trailer home was forcibly removed, id., at 62, no Fourth Amendment violation occurred because law enforcement had not “invade[d] the [individuals’] privacy,” id., at 60. Katz, the Court explained, established that “property rights are not the sole measure of Fourth Amendment violations,” but did not “snuf[f] out the previously recognized protection for property.” 506 U. S., at 64. As Justice Brennan explained in his concurrence in Knotts, Katz did not erode the principle “that, when the Government does engage in physical intrusion of a constitutionally protected area in order to obtain information, that intrusion may constitute a violation of the Fourth Amendment.” 460 U. S., at 286 (opinion concurring in judgment). We have embodied that preservation *408of past rights in our very definition of “reasonable expectation of privacy” which we have said to be an expectation “that has a source outside of the Fourth Amendment, either by reference to concepts of real or personal property law or to understandings that are recognized and permitted by society.” Minnesota v. Carter, 525 U. S. 83, 88 (1998) (internal quotation marks omitted). Katz did not narrow the Fourth Amendment’s scope.5

The Government contends that several of our post-Aate cases foreclose the conclusion that what occurred here constituted a search. It relies principally on two cases in which we rejected Fourth Amendment challenges to “beepers,” electronic tracking devices that represent another form of electronic monitoring. The first ease, Knotts, upheld against Fourth Amendment challenge the use of a “beeper” that had been placed in a container of chloroform, allowing law enforcement to monitor the location of the container. 460 U. S., at 278. We said that there had been no infringement of Knotts’ reasonable expectation of privacy since the information obtained — the location of the automobile carry*409ing the container on public roads, and the location of the offloaded container in open fields near Knotts’ cabin — had been voluntarily conveyed to the public.6 Id., at 281-282. But as we have discussed, the Katz reasonable-expeetation-of-privacy test has been added to, not substituted for, the common-law trespassory test. The holding in Knotts addressed only the former, since the latter was not at issue. The beeper had been placed in the container before it came into Knotts’ possession, with the consent of the then-owner. 460 U. S., at 278. Knotts did not challenge that installation, and we specifically declined to consider its effect on the Fourth Amendment analysis. Id., at 279, n. Knotts would be relevant, perhaps, if the Government were making the argument that what would otherwise be an unconstitutional search is not such where it produces only public information. The Government does not make that argument, and we know of no case that would support it.

The second “beeper” case, United States v. Karo, 468 U. S.-705 (1984), does not suggest a different conclusion. There we addressed the question left open by Knotts, whether the installation of a beeper in a container amounted to a search or seizure. 468 U. S., at 713. As in Knotts, at the time the beeper was installed the container belonged to a third party, and it did not come into possession of the defendant until later. 468 U. S., at 708. Thus, the specific question we considered was whether the installation “with the consent of the original owner constitute^] a search or seizure . . . when the container is delivered to a buyer having no knowledge of the presence of the beeper.” Id., at 707 (emphasis added). We held not. The Government, we said, came into physical contact with the container only before it belonged to the de*410fendant Karo; and the transfer of the container with the unmonitored beeper inside did not convey any information and thus did not invade Karo’s privacy. See id., at 712. That conclusion is perfectly consistent with the one we reach here. Karo accepted the container as it came to him, beeper and all, and was therefore not entitled to object to the beeper’s presence, even though it was used to monitor the container’s location. Cf. On Lee v. United States, 343 U. S. 747, 751-752 (1952) (no search or seizure where an informant, who was wearing a concealed microphone, was invited into the defendant’s business). Jones, who possessed the Jeep at the time the Government trespassorily inserted the information-gathering device, is on much different footing.

The Government also points to our exposition in New York v. Class, 475 U. S. 106 (1986), that “[t]he exterior of a car . .. is thrust into the public eye, and thus to examine it does not constitute a ‘search.’ ” Id., at 114. That statement is of marginal relevance here since, as the Government acknowledges, “the officers in this ease did more than conduct a visual inspection of respondent’s vehicle,” Brief for United States 41 (emphasis added). By attaching the device to the Jeep, officers encroached on a protected area. In Class itself we suggested that this would make a difference, for we concluded that an officer’s momentary reaching into the interior of a vehicle did constitute a search.7 475 U. S., at 114-115.

Finally, the Government’s position gains little support from our conclusion in Oliver v. United States, 466 U. S. 170 *411(1984), that officers’ information-gathering intrusion on an “open field” did not constitute a Fourth Amendment search even though it was a trespass at common law, id., at 183. Quite simply, an open field, unlike the curtilage of a home, see United States v. Dunn, 480 U. S. 294, 300 (1987), is not one of those protected areas enumerated in the Fourth Amendment. Oliver, supra, at 176-177. See also Hester v. United States, 265 U. S. 57, 59 (1924). The Government’s physical intrusion on such an area — unlike its intrusion on the “effect” at issue here — is of no Fourth Amendment significance.8

B

The concurrence begins by accusing us of applying “18th-century tort law.” Post, at 418. That is a distortion. What we apply is an 18th-century guarantee against unreasonable searches, which we believe must provide at a minimum the degree of protection it afforded when it was adopted. The concurrence does not share that belief. It would apply exclusively Katz’s reasonable-expectation-of-privacy test, even when that eliminates rights that previously existed.

The concurrence faults our approach for “presenting] particularly vexing problems” in cases that do not involve physical contact, such as those that involve the transmission of electronic signals. Post, at 426. We entirely fail to understand that point. For unlike the concurrence, which would make Katz the exclusive test, we do not make trespass the exclusive test. Situations involving merely the transmission of electronic signals without trespass would remain subject to Katz analysis.

*412In fact, it is the concurrence’s insistence on the exclusivity of the Katz test that needlessly leads us into “particularly vexing problems” in the present case. This Court has to date not deviated from the understanding that mere visual observation does not constitute a search. See Kyllo, 533 U. S., at 31-32. We accordingly held in Knotts that “[a] person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another.” 460 U. S., at 281. Thus, even assuming that the concurrence is correct to say that “[tjraditional surveillance” of Jones for a 4-week period “would have required a large team of agents, multiple vehicles, and perhaps aerial assistance,” post, at 429, our cases suggest that such visual observation is constitutionally permissible. It may be that achieving the same result through electronic means, without an accompanying trespass, is an unconstitutional invasion of privacy, but the present case does not require us to answer that question.

And answering it affirmatively leads us needlessly into additional thorny problems. The concurrence posits that “relatively short-term monitoring of a person’s movements on public streets” is okay, but that “the use of longer term GPS monitoring in investigations of most offenses” is no good. Post, at 430 (emphasis added). That introduces yet another novelty into our jurisprudence. There is no precedent for the proposition that whether a search has occurred depends on the nature of the crime being investigated. And even accepting that novelty, it remains unexplained why a 4-week investigation is “surely” too long and why a drug-trafficking conspiracy involving substantial amounts of cash and narcotics is not an “extraordinary offens[e]” which may permit longer observation. See post, at 430-431. What of a 2-day monitoring of a suspected purveyor of stolen electronics? Or of a 6-month monitoring of a suspected terrorist? We may have to grapple with these “vexing problems” in some future case where a classic trespassory search is not involved *413and resort must be had to Katz analysis; but there is no reason for rushing forward to resolve them here.

III

The Government argues in the alternative that even if the attachment and use of the device was a search, it was reasonable — and thus lawful — under the Fourth Amendment because “officers had reasonable suspicion, and indeed probable cause, to believe that [Jones] was a leader in a large-scale cocaine distribution conspiracy.” Brief for United States 50-51. We have no occasion to consider this argument. The Government did not raise it below, and the D. C. Circuit therefore did not address it. See 625 F. 3d, at 767 (Ginsburg, Tatel, and Griffith, JJ., concurring in denial of rehearing en banc). We consider the argument forfeited. See Sprietsma v. Mercury Marine, 537 U. S. 51, 56, n. 4 (2002).

* * *

The judgment of the Court of Appeals for the D. C. Circuit is affirmed.

It is so ordered.

Justice Sotomayor,

concurring.

I join the Court’s opinion because I agree that a search within the meaning of the Fourth Amendment occurs, at a minimum, “[w]here, as here, the Government obtains information by physically intruding on a constitutionally protected area.” Ante, at 406-407, n. 3. In this case, the Government installed a Global Positioning System (GPS) tracking device on respondent Antoine Jones’ Jeep without a valid warrant and without Jones’ consent, then used that device to monitor the Jeep’s movements over the course of four weeks. The Government usurped Jones’ property for the purpose of conducting surveillance on him, thereby invading privacy interests long afforded, and undoubtedly entitled to, Fourth *414Amendment protection. See, e. g., Silverman v. United States, 365 U. S. 505, 511-512 (1961).

Of course, the Fourth Amendment is not concerned only with trespassory intrusions on property. See, e. g., Kyllo v. United States, 533 U. S. 27, 31-33 (2001). Rather, even in the absence of a trespass, “a Fourth Amendment search occurs when the government violates a subjective expectation of privacy that society recognizes as reasonable.” Id., at 33; see also Smith v. Maryland, 442 U. S. 735, 740-741 (1979); Katz v. United States, 389 U. S. 347, 361 (1967) (Harlan, J., concurring). In Katz, this Court enlarged its then-prevailing focus on property rights by announcing that the reach of the Fourth Amendment does not “turn upon the presence or absence of a physical intrusion.” Id., at 353. As the majority’s opinion makes clear, however, Katz’s reasonable-expectation-of-privacy test augmented, but did not displace or diminish, the common-law trespassory test that preceded it. Ante, at 409. Thus, “when the Government does engage in physical intrusion of a constitutionally protected area in order to obtain information, that intrusion may constitute a violation of the Fourth Amendment.” United States v. Knotts, 460 U. S. 276, 286 (1983) (Brennan, J., concurring in judgment); see also, e. g., Rakas v. Illinois, 439 U. S. 128, 144, n. 12 (1978). Justice Alito’s approach, which discounts altogether the constitutional relevance of the Government’s physical intrusion on Jones’ Jeep, erodes that longstanding protection for privacy expectations inherent in items of property that people possess or control. See post, at 422-424 (opinion concurring in judgment). By contrast, the trespassory test applied in the majority’s opinion reflects an irreducible constitutional minimum: When the government physically invades personal property to gather information, a search occurs. The reaffirmation of that principle suffices to decide this case.

Nonetheless, as Justice Alito notes, physical intrusion is now unnecessary to many forms of surveillance. Post, at *415426-429. With increasing regularity, the government will be capable of duplicating the monitoring undertaken in this case by enlisting factory- or owner-installed vehicle tracking devices or GPS-enabled smartphones. See United States v. Pineda-Moreno, 617 F. 3d 1120, 1125 (CA9 2010) (Kozinski, C. J., dissenting from denial of rehearing en banc). In cases of electronic or other novel modes of surveillance that do not depend upon a physical invasion on property, the majority opinion’s trespassory test may provide little guidance. But “[situations involving merely the transmission of electronic signals without trespass would remain subject to Katz analysis.” Ante, at 411. As Justice Alito incisively observes, the same technological advances that have made possible nontrespassory surveillance techniques will also affect the Katz test by shaping the evolution of societal privacy expectations. Post, at 428. Under that rubric, I agree with Justice Alito that, at the very least, “longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy.” Post, at 430.

In cases involving even short-term monitoring, some unique attributes of GPS surveillance relevant to the Katz analysis will require particular attention. GPS monitoring generates a precise, comprehensive record of a person’s public movements that reflects a wealth of detail about her familial, political, professional, religious, and sexual associations. See, e. g., People v. Weaver, 12 N. Y. 3d 433, 441-442, 909 N. E. 2d 1195, 1199 (2009) (“Disclosed in [GPS] data . . . will be trips the indisputably private nature of which takes little imagination to conjure: trips to the psychiatrist, the plastic surgeon, the abortion clinic, the AIDS treatment center, the strip club, the criminal defense attorney, the by-the-hour motel, the union meeting, the mosque, synagogue or church, the gay bar and on and on”). The government can store such records and efficiently mine them for information years into the future. Pineda-Moreno, 617 F. 3d, at 1124 (opinion of Kozinski, C. J.). And because GPS monitoring is *416cheap in comparison to conventional surveillance techniques and, by design, proceeds surreptitiously, it evades the ordinary checks that constrain abusive law enforcement practices: “limited police resources and community hostility.” Illinois v. Lidster, 540 U. S. 419, 426 (2004)..

Awareness that the government may be watching chills associational and expressive freedoms. And the government’s unrestrained power to assemble data that reveal private aspects of identity is susceptible to abuse. The net result is that GPS monitoring — by making available at a relatively low cost such a substantial quantum of intimate information about any person whom the government, in its unfettered discretion, chooses to track — may “alter the relationship between citizen and government in a way that is inimical to democratic society.” United States v. Cuevas-Perez, 640 F. 3d 272, 285 (CA7 2011) (Flaum, J., concurring).

I would take these attributes of GPS monitoring into account when considering the existence of a reasonable societal expectation of privacy in the sum of one’s public movements. I would ask whether people reasonably expect that their movements will be recorded and aggregated in a manner that enables the government to ascertain, more or less at will, their political and religious beliefs, sexual habits, and so on. I do not regard as dispositive the fact that the government might obtain the fruits of GPS monitoring through lawful conventional surveillance techniques. See Kyllo, 533 U. S., at 35, n. 2; ante, at 412 (leaving open the possibility that duplicating traditional surveillance “through electronic means, without an accompanying trespass, is an unconstitutional invasion of privacy”). I would also consider the appropriateness of entrusting to the Executive, in the absence of any oversight from a coordinate branch, a tool so amenable to misuse, especially in light of the Fourth Amendment’s goal to curb arbitrary exercises of police power and prevent “a *417too permeating police surveillance,” United States v. Di Re, 332 U. S. 581, 595 (1948).*

More fundamentally, it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties. E. g., Smith, 442 U. S., at 742; United States v. Miller, 425 U. S. 435, 443 (1976). This approach is ill suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks. People disclose the phone numbers that they dial or text to their cellular providers; the URLs that they visit and the e-mail addresses with which they correspond to their Internet service providers; and the books, groceries, and medications they purchase to online retailers. Perhaps, as Justice Alito notes, some people may find the “tradeoff” of privacy for convenience “worthwhile,” or come to accept this “diminution of privacy” as “inevitable,” post, *418at 427, and perhaps not. I for one doubt that people would accept without complaint the warrantless disclosure to the government of a list of every Web site they had visited in the last week, or month, or year. But whatever the societal expectations, they can attain constitutionally protected status only if our Fourth Amendment jurisprudence ceases to treat secrecy as a prerequisite for privacy. I would not assume that all information voluntarily disclosed to some member of the public for a limited purpose is, for that reason alone, disentitled to Fourth Amendment protection. See Smith, 442 U. S., at 749 (Marshall, J., dissenting) (“Privacy is not a discrete commodity, possessed absolutely or not at all. Those who disclose certain facts to a bank or phone company for a limited business purpose need not assume that this information will be released to other persons for other purposes”); see also Katz, 389 U. S., at 351-352 (“[W]hat [a person] seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected”).

Resolution of these difficult questions in this case is unnecessary, however, because the Government’s physical intrusion on Jones’ Jeep supplies a narrower basis for decision. I therefore join the majority’s opinion.

Justice Alito,

with whom Justice Ginsburg, Justice Breyer, and Justice Kagan join,

concurring in the judgment.

This case requires us to apply the Fourth Amendment’s prohibition of unreasonable searches and seizures to a 21st-century surveillance technique, the use of a Global Positioning System (GPS) device to monitor a vehicle’s movements for an extended period of time. Ironically, the Court has chosen to decide this case based on 18th-century tort law. By attaching a small GPS device1 to the underside of the *419vehicle that respondent drove, the law enforcement officers in this case engaged in conduct that might have provided grounds in 1791 for a suit for trespass to chattels.2 And for this reason, the Court concludes, the installation and use of the GPS device constituted a search. Ante, at 404-405.

This holding, in my judgment, is unwise. It strains the language of the Fourth Amendment; it has little if any support in current Fourth Amendment case law; and it is highly artificial.

I would analyze the question presented in this case by asking whether respondent’s reasonable expectations of privacy were violated by the long-term monitoring of the movements of the vehicle he drove.

I — l

A

The Fourth Amendment prohibits “unreasonable searches and seizures,” and the Court makes very little effort to explain how the attachment or use of the GPS device fits within these terms. The Court does not contend that there was a seizure. A seizure of property occurs when there is “some meaningful interference with an individual’s possessory interests in that property,” United States v. Jacobsen, 466 U. S. 109, 113 (1984), and here there was none. Indeed, the success of the surveillance technique that the officers employed was dependent on the fact that the GPS did not interfere in any way with the operation of the vehicle, for if any such interference had been detected, the device might have been discovered.

*420The Court does claim that the installation and use of the GPS constituted a search, see ante, at 404-405, but this conclusion is dependent on the questionable proposition that these two procedures cannot be separated for purposes of Fourth Amendment analysis. If these two procedures are analyzed separately, it is not at all clear from the Court’s opinion why either should be regarded as a search. It is clear that the attachment of the GPS device was not itself a search; if the device had not functioned or if the officers had not used it, no information would have been obtained. And the Court does not contend that the use of the device constituted a search either. On the contrary, the Court accepts the holding in United States v. Knotts, 460 U. S. 276 (1983), that the use of a surreptitiously planted electronic device to monitor a vehicle’s movements on public roads did not amount to a search. See ante, at 408-409.

The Court argues — and I agree — that “we must ‘assur[e] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted.’” Ante, at 406 (quoting Kyllo v. United States, 533 U. S. 27, 34 (2001)). But it is almost impossible to think of late-18thcentury situations that are analogous to what took place in this case. (Is it possible to imagine a case in which a constable secreted himself somewhere in a coach and remained there for a period of time in order to monitor the movements of the coach’s owner?3) The Court’s theory seems to be that the concept of a search, as originally understood, comprehended any technical trespass that led to the gathering of evidence, but we know that this is incorrect. At common law, any unauthorized intrusion on private property was actionable, see Prosser & Keeton 75, but a trespass on open fields, as opposed to the “curtilage” of a home, does not fall *421within the scope of the Fourth Amendment because private property outside the curtilage is not part of a “hous[e]” within the meaning of the Fourth Amendment. See Oliver v. United States, 466 U. S. 170 (1984); Hester v. United States, 265 U. S. 57 (1924).

B

The Court’s reasoning in this case is very similar to that in the Court’s early decisions involving wiretapping and electronic eavesdropping, namely, that a technical trespass followed by the gathering of evidence constitutes a search. In the early electronic surveillance cases, the Court concluded that a Fourth Amendment search occurred when private conversations were monitored as a result of an “unauthorized physical penetration into the premises occupied” by the defendant. Silverman v. United States, 365 U. S. 505, 509 (1961). In Silverman, police officers listened to conversations in an attached home by inserting a “spike mike” through the wall that this house shared with the vacant house next door. Id., at 506. This procedure was held to be a search because the mike made contact with a heating duct on the other side of the wall and thus “usurpfed] ... an integral part of the premises.” Id., at 511.

By contrast, in cases in which there was no trespass, it was held that there was no search. Thus, in Olmstead v. United States, 277 U. S. 438 (1928), the Court found that the Fourth Amendment did not apply because “[t]he taps from house lines were made in the streets near the houses.” Id., at 457. Similarly, the Court concluded that no search occurred in Goldman v. United States, 316 U. S. 129,135 (1942), where a “detectaphone” was placed on the outer wall of defendant’s office for the purpose of overhearing conversations held within the room.

This trespass-based rule was repeatedly criticized. In Olmstead, Justice Brandéis wrote that it was “immaterial where the physical connection with the telephone wires . . . was made.” 277 U. S., at 479 (dissenting opinion). Al*422though a private conversation transmitted by wire did not fall within the literal words of the Fourth Amendment, he argued, the Amendment should be understood as prohibiting “every unjustifiable intrusion by the Government upon the privacy of the individual.” Id., at 478. See also, e. g., Sil-verman, supra, at 513 (Douglas, J., concurring) (“The concept of ‘an unauthorized physical penetration into the premises/ on which the present decision rests, seems to me beside the point. Was not the wrong ... done when the intimacies of the home were tapped, recorded, or revealed? The depth of the penetration of the electronic device — even the degree of its remoteness from the inside of the house — is not the measure of the injury”); Goldman, supra, at 139 (Murphy, J., dissenting) (“[Tjhe search of one’s home or office no longer requires physical entry, for science has brought forth far more effective devices for the invasion of a person’s privacy than the direct and obvious methods of oppression which were detested by our forebears and which inspired the Fourth Amendment”).

Katz v. United States, 389 U. S. 347 (1967), finally did away with the old approach, holding that a trespass was not required for a Fourth Amendment violation. Katz involved the use of a listening device that was attached to the outside of a public telephone booth and that allowed police officers to eavesdrop on one end of the target’s phone conversation. This procedure did not physically intrude on the area occupied by the target, but the Katz Court “repudiate[ed]” the old doctrine, Rakas v. Illinois, 439 U. S. 128, 143 (1978), and held that “[t]he fact that the electronic device employed . . . did not happen to penetrate the wall of the booth can have no constitutional significance,” 389 U. S., at 353; ibid. (“[T]he reach of th[e] [Fourth] Amendment cannot turn upon the presence or absence of a physical intrusion into any given enclosure”); see Rakas, supra, at 143 (describing Katz as holding that the “capacity to claim the protection for the Fourth Amendment depends not upon a property right in *423the invaded place but upon whether the person who claims the protection of the Amendment has a legitimate expectation of privacy in the invaded place”); Kyllo, 533 U. S., at 32 (“We have since decoupled violation of a person’s Fourth Amendment rights from trespassory violation of his property”). What mattered, the Court now held, was whether the conduct at issue “violated the privacy upon which [the defendant] justifiably relied while using the telephone booth.” Katz, supra, at 353.

Under this approach, as the Court later put it when addressing the relevance of a technical trespass, “an actual trespass is neither necessary nor sufficient to establish a constitutional violation.” United States v. Karo, 468 U. S. 705, 713 (1984) (emphasis added). Ibid. (“[e]ompar[ing] Katz v. United States, 389 U. S. 347 (1967) (no trespass, but Fourth Amendment violation), with Oliver v. United States, 466 U. S. 170 (1984) (trespass, but no Fourth Amendment violation)”). In Oliver, the Court wrote:

“The existence of a property right is but one element in determining whether expectations of privacy are legitimate. ‘The premise that property interests control the right of the Government to search and seize has been discredited.’ Katz, 389 U. S., at 353 (quoting Warden v. Hayden, 387 U. S. 294, 304 (1967).” 466 U. S., at 183 (some internal quotation marks omitted).

FH FH

The majority suggests that two post-Katz decisions— Soldal v. Cook County, 506 U. S. 56 (1992), and Alderman v. United States, 394 U. S. 165 (1969) — show that a technical trespass is sufficient to establish the existence of a search, but they provide little support.

In Soldal, the Court held that towing away a trailer home without the owner’s consent constituted a seizure even if this did not invade the occupants’ personal privacy. But in the *424present case, the Court does not find that there was a seizure, and it is clear that none occurred.

In Alderman, the Court held that the Fourth Amendment rights of homeowners were implicated by the use of a surreptitiously planted listening device to monitor third-party conversations that occurred within their home. See 394 U. S., at 176-180. Alderman is best understood to mean that the homeowners had a legitimate expectation of privacy in all conversations that took place under their roof. See Rakas, supra, at 144, n. 12 (citing Alderman for the proposition that “the Court has not altogether abandoned use of property concepts in determining the presence or absence of the privacy interests protected by that Amendment”); 439 U. S., at 153 (Powell, J., concurring) (citing Alderman for the proposition that “property rights reflect society’s explicit recognition of a person’s authority to act as he wishes in certain areas, and therefore should be considered in determining whether an individual’s expectations of privacy are reasonable); Karo, supra, at 732 (Stevens, J., concurring in part and dissenting in part) (citing Alderman in support of the proposition that “a homeowner has a reasonable expectation of privacy in the contents of his home, including items owned by others”).

In sum, the majority is hard pressed to find support in post-Katz cases for its trespass-based theory.

1 — I HH HH

Disharmony with a substantial body of existing ease law is only one of the problems with the Court’s approach in this case.

I will briefly note four others. First, the Court’s reasoning largely disregards what is really important (the use of a GPS for the purpose of long-term tracking) and instead attaches great significance to something that most would view as relatively minor (attaching to the bottom of a car a small, light object that does not interfere in any way with the car’s *425operation). Attaching such an object is generally regarded as so trivial that it does not provide a basis for recovery under modern tort law. See Prosser & Keeton § 14, at 87 (harmless or trivial contact with personal property not actionable); D. Dobbs, Law of Torts 124 (2000) (same). But under the Court’s reasoning, this conduct may violate the Fourth Amendment. By contrast, if long-term monitoring can be accomplished without committing a technical trespass — suppose, for example, that the Federal Government required or persuaded auto manufacturers to include a GPS tracking device in every car — the Court’s theory would provide no protection.

Second, the Court’s approach leads to incongruous results. If the police attach a GPS device to a car and use the device to follow the car for even a brief time, under the Court’s theory, the Fourth Amendment applies. But if the police follow the same car for a much longer period using unmarked cars and aerial assistance, this tracking is not subject to any Fourth Amendment constraints.

In the present case, the Fourth Amendment applies, the Court concludes, because the officers installed the GPS device after respondent’s wife, to whom the car was registered, turned it over to respondent for his exclusive use. See ante, at 404-405. But if the GPS had been attached prior to that time, the Court’s theory would lead to a different result. The Court proceeds on the assumption that respondent “had at least the property rights of a bailee,” ante, at 404, n. 2, but a bailee may sue for a trespass to chattel only if the injury occurs during the term of the bailment. See 8A Am. Jur. 2d, Bailment § 166, pp. 685-686 (2009). So if the GPS device had been installed before respondent’s wife gave him the keys, respondent would have no claim for trespass — and, presumably, no Fourth Amendment claim either.

Third, under the Court’s theory, the coverage of the Fourth Amendment may vary from State to State. If the events at issue here had occurred in a community-property *426State4 or a State that has adopted the Uniform Marital Property Act,5 respondent would likely be an owner of the vehicle, and it would not matter whether the GPS was installed before or after his wife turned over the keys. In non-community-property States, on the other hand, the registration of the vehicle in the name of respondent’s wife would generally be regarded as presumptive evidence that she was the sole owner. See 60 C. J. S., Motor Vehicles § 231, pp. 398-399 (2002); 8 Am. Jur. 2d, Automobiles § 1208, pp. 859-860 (2007).

Fourth, the Court’s reliance on the law of trespass will present particularly vexing problems in cases involving surveillance that is carried out by making electronic, as opposed to physical, contact with the item to be tracked. For example, suppose that the officers in the present case had followed respondent by surreptitiously activating a stolen vehicle detection system that came with the car when it was purchased. Would the sending of a radio signal to activate this system constitute a trespass to chattels? Trespass to chattels has traditionally required a physical touching of the property. See Restatement (Second) of Torts §217 and Comment e (1963 and 1964); Dobbs, supra, at 123. In recent years, courts have wrestled with the application of this old tort in cases involving unwanted electronic contact with computer systems, and some have held that even the transmission of electrons that occurs when a communication is sent from one computer to another is enough. See, e. g., CompuServe, Inc. v. Cyber Promotions, Inc. 962 F. Supp. 1015, 1021 (SD Ohio 1997); Thrifty-Tel, Inc. v. Bezenek, 46 Cal. App. 4th 1559,1566, n. 6, 54 Cal. Rptr. 2d 468, 473, n. 6 (1996). But may such decisions be followed in applying the Court’s trespass theory? Assuming that what matters under the Court’s theory is the law of trespass as it existed at the time of the adoption of the Fourth Amendment, do these recent *427decisions represent a change in the law or simply the application of the old tort to new situations?

IV

A

The Katz expectation-of-privacy test avoids the problems and complications noted above,- but it is not without its own difficulties. It involves a degree of circularity, see Kyllo, 533 U. S., at 34, and judges are apt to confuse their own expectations of privacy with those of the hypothetical reasonable person to which the Katz test looks. See Minnesota v. Carter, 525 U. S. 83, 97 (1998) (Scalia, J., concurring). In addition, the Katz test rests on the assumption that this hypothetical reasonable person has a well-developed and stable set of privacy expectations. But technology can change those expectations. Dramatic technological change may lead to periods in which popular expectations are in flux and may ultimately produce significant changes in popular attitudes. New technology may provide increased convenience or security at the expense of privacy, and many people may find the tradeoff worthwhile. And even if the public does not welcome the diminution of privacy that new technology entails, they may eventually reconcile themselves to this development as inevitable.6

On the other hand, concern about new intrusions on privacy may spur the enactment of legislation to protect against these intrusions. This is what ultimately happened with respect to wiretapping. After Katz, Congress did not leave it to the courts to develop a body of Fourth Amendment case law governing that complex subject. Instead, Congress promptly enacted a comprehensive statute, see 18 U. S. C. *428§§2510-2522 (2006 ed. and Supp. IV), and since that time, the regulation of wiretapping has been governed primarily by statute and not by case law.7 In an ironic sense, although Katz overruled Olmstead, Chief Justice Taft’s suggestion in the latter case that the regulation of wiretapping was a matter better left for Congress, see 277 U. S., at 465-466, has been borne out.

B

Recent years have seen the emergence of many new devices that permit the monitoring of a person’s movements. In some locales, closed-circuit television video monitoring is becoming ubiquitous. On toll roads, automatic toll collection systems create a precise record of the movements of motorists who choose to make use of that convenience. Many motorists purchase cars that are equipped with devices that permit a central station to ascertain the car’s location at any time so that roadside assistance may be provided if needed and the car may be found if it is stolen.

Perhaps most significant, cell phones and other wireless devices now permit wireless carriers to track and record the location of users — and as of June 2011, it has been reported, there were more than 322 million wireless devices in use in the United States.8 For older phones, the accuracy of the location information depends on the density of the tower network, but new “smart phones,” which are equipped with a GPS device, permit more precise tracking. For example, when a user activates the GPS on such a phone, a provider is able to monitor the phone’s location and speed of movement and can then report back real-time traffic conditions after combining (“crowdsourcing”) the speed of all such *429phones on any particular road.9 Similarly, phone-location-tracking services are offered as “social” tools, allowing consumers to find (or to avoid) others who enroll in these services. The availability and use of these and other new devices will continue to shape the average person’s expectations about the privacy of his or her daily movements.

V

In the precomputer age, the greatest protections of privacy were neither constitutional nor statutory, but practical. Traditional surveillance for any extended period of time was difficult and costly and therefore rarely undertaken. The surveillance at issue in this case — constant monitoring of the location of a vehicle for four weeks — would have required a large team of agents, multiple vehicles, and perhaps aerial assistance.10 Only an investigation of unusual importance could have justified such an expenditure of law enforcement resources. Devices like the one used in the present case, however, make long-term monitoring relatively easy and cheap. In circumstances involving dramatic technological change, the best solution to privacy concerns may be legislative. See, e.g., Kerr 805-806. A legislative body is well situated to gauge changing public attitudes, to draw detailed *430lines, and to balance privacy and public safety in a comprehensive way.

To date, however, Congress and most States have not enacted statutes regulating the use of GPS tracking technology for law enforcement purposes. The best that we can do in this case is to apply existing Fourth Amendment doctrine and to ask whether the use of GPS tracking in a particular case involved a degree of intrusion that a reasonable person would not have anticipated.

Under this approach, relatively short-term monitoring of a person’s movements on public streets accords with expectations of privacy that our society has recognized as reasonable. See Knotts, 460 U. S., at 281-282. But the use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy. For such offenses, society’s expectation has been that law enforcement agents and others would not — and indeed, in the main, simply could not — secretly monitor and catalogue every single movement of an individual’s car for a very long period. In this case, for four weeks, law enforcement agents tracked every movement that respondent made in the vehicle he was driving. We need not identify with precision the point at which the tracking of this vehicle became a search, for the line was surely crossed before the 4-week mark. Other cases may present more difficult questions. But where uncertainty exists with respect to whether a certain period of GPS surveillance is long enough to constitute a Fourth Amendment search, the police may always seek a warrant.11 *431We also need not consider whether prolonged GPS monitoring in the context of investigations involving extraordinary offenses would similarly intrude on a constitutionally protected sphere of privacy. In such cases, long-term tracking might have been mounted using previously available techniques.

* * *

For these reasons, I conclude that the lengthy monitoring that occurred in this case constituted a search under the Fourth Amendment. I therefore agree with the majority that the decision of the Court of Appeals must be affirmed.