Justice Scalia delivered the opinion of the Court.

     We consider whether using a drug-sniffing dog on a homeowner's porch to investigate the contents of the home is a "search" within the meaning of the Fourth Amendment.

I

     In 2006, Detective William Pedraja of the Miami-Dade Police Department received an unverified tip that marijuana was being grown in the home of respondent Joelis Jardines. One month later, the Department and the Drug Enforcement Administration sent a joint surveillance team to Jardines' home. Detective Pedraja was part of that team. He watched the home for fifteen minutes and saw no vehicles in the driveway or activity around the home, and could not see inside because the blinds were drawn.      Detective Pedraja then approached Jardines' home accompanied by Detective Douglas Bartelt, a trained canine handler who had just arrived at the scene with his drug-sniffing dog. The dog was trained to detect the scent of marijuana, cocaine, heroin, and several other drugs, indicating the presence of any of these substances through particular behavioral changes recognizable by his handler.

     Detective Bartelt had the dog on a six-foot leash, owing in part to the dog's "wild" nature, App. to Pet. for Cert. A-35, and tendency to dart around erratically while searching. As the dog approached Jardines' front porch, he apparently sensed one of the odors he had been trained to detect, and began energetically exploring the area for the strongest point source of that odor. As Detective Bartelt explained, the dog "began tracking that airborne odor by . . . tracking back and forth," engaging in what is called "bracketing," "back and forth, back and forth." Id., at A- 33 to A-34. Detective Bartelt gave the dog "the full six feet of the leash plus whatever safe distance [he could] give him" to do this--he testified that he needed to give the dog "as much distance as I can." Id., at A-35. And Detective Pedraja stood back while this was occurring, so that he would not "get knocked over" when the dog was "spinning around trying to find" the source. Id., at A-38.

     After sniffing the base of the front door, the dog sat, which is the trained behavior upon discovering the odor's strongest point. Detective Bartelt then pulled the dog away from the door and returned to his vehicle. He left the scene after informing Detective Pedraja that there had been a positive alert for narcotics.

     On the basis of what he had learned at the home, Detective Pedraja applied for and received a warrant to search the residence. When the warrant was executed later that day, Jardines attempted to flee and was arrested; the search revealed marijuana plants, and he was charged with trafficking in cannabis.

     At trial, Jardines moved to suppress the marijuana plants on the ground that the canine investigation was an unreasonable search. The trial court granted the motion, and the Florida Third District Court of Appeal reversed. On a petition for discretionary review, the Florida Supreme Court quashed the decision of the Third District Court of Appeal and approved the trial court's decision to suppress, holding (as relevant here) that the use of the trained narcotics dog to investigate Jardines' home was a Fourth Amendment search unsupported by probable cause, rendering invalid the warrant based upon information gathered in that search. 73 So. 3d 34 (2011).

     We granted certiorari, limited to the question of whether the officers' behavior was a search within the meaning of the Fourth Amendment. 565 U. S. ___ (2012).

II

     The Fourth Amendment provides in relevant part 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." The Amendment establishes a simple baseline, one that for much of our history formed the exclusive basis for its protections: When "the Government obtains information by physically intruding" on persons, houses, papers, or effects, "a 'search' within the original meaning of the Fourth Amendment" has "undoubtedly occurred." United States v. Jones, 565 U. S. ___, ___, n. 3 (2012) (slip op., at 6, n. 3). By reason of our decision in Katz v. United States, 389 U. S. 347 (1967), property rights "are not the sole measure of Fourth Amendment violations," Soldal v. Cook County, 506 U. S. 56, 64 (1992)--but though Katz may add to the baseline, it does not subtract anything from the Amendment's protections "when the Government does engage in [a] physical intrusion of a constitutionally protected area," United States v. Knotts, 460 U. S. 276, 286 (1983) (Brennan, J., concurring in the judgment).

     That principle renders this case a straightforward one. The officers were gathering information in an area belonging to Jardines and immediately surrounding his house--in the curtilage of the house, which we have held enjoys protection as part of the home itself. And they gathered that information by physically entering and occupying the area to engage in conduct not explicitly or implicitly permitted by the homeowner.

A

     The Fourth Amendment "indicates with some precision the places and things encompassed by its protections": persons, houses, papers, and effects. Oliver v. United States, 466 U. S. 170, 176 (1984). The Fourth Amendment does not, therefore, prevent all investigations conducted on private property; for example, an officer may (subject to Katz) gather information in what we have called "open fields"--even if those fields are privately owned--because such fields are not enumerated in the Amendment's text. Hester v. United States, 265 U. S. 57 (1924).

     But when it comes to the Fourth Amendment, the home is first among equals. At the Amendment's "very core" 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). This right would be of little practical value if the State's agents could stand in a home's porch or side garden and trawl for evidence with impunity; the right to retreat would be significantly diminished if the police could enter a man's property to observe his repose from just outside the front window.

     We therefore regard the area "immediately surrounding and associated with the home"--what our cases call the curtilage--as "part of the home itself for Fourth Amendment purposes." Oliver, supra, at 180. That principle has ancient and durable roots. Just as the distinction between the home and the open fields is "as old as the common law," Hester, supra, at 59, so too is the identity of home and what Blackstone called the "curtilage or homestall," for the "house protects and privileges all its branches and appurtenants." 4 W. Blackstone, Commentaries on the Laws of England 223, 225 (1769). This area around the home is "intimately linked to the home, both physically and psychologically," and is where "privacy expectations are most heightened." California v. Ciraolo, 476 U. S. 207, 213 (1986).

     While the boundaries of the curtilage are generally "clearly marked," the "conception defining the curtilage" is at any rate familiar enough that it is "easily understood from our daily experience." Oliver, 466 U. S., at 182, n. 12. Here there is no doubt that the officers entered it: The front porch is the classic exemplar of an area adjacent to the home and "to which the activity of home life extends." Ibid.

B

     Since the officers' investigation took place in a constitutionally protected area, we turn to the question of whether it was accomplished through an unlicensed physical intrusion.¹ While law enforcement officers need not "shield their eyes" when passing by the home "on public thoroughfares," Ciraolo, 476 U. S., at 213, an officer's leave to gather information is sharply circumscribed when he steps off those thoroughfares and enters the Fourth Amendment's protected areas. In permitting, for example, visual observation of the home from "public navigable airspace," we were careful to note that it was done "in a physically nonintrusive manner." Ibid. Entick v. Carrington, 2 Wils. K. B. 275, 95 Eng. Rep. 807 (K. B. 1765), a case "undoubtedly familiar" to "every American statesman" at the time of the Founding, Boyd v. United States, 116 U. S. 616, 626 (1886), states the general rule clearly: "[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." 2 Wils. K. B., at 291, 95 Eng. Rep., at 817. As it is undisputed that the detectives had all four of their feet and all four of their companion's firmly planted on the constitutionally protected extension of Jardines' home, the only question is whether he had given his leave (even implicitly) for them to do so. He had not.

     "A license may be implied from the habits of the country," notwithstanding the "strict rule of the English common law as to entry upon a close." McKee v. Gratz, 260 U. S. 127, 136 (1922) (Holmes, J.). We have accordingly recognized that "the knocker on the front door is treated as an invitation or license to attempt an entry, justifying ingress to the home by solicitors, hawkers and peddlers of all kinds." Breard v. Alexandria, 341 U. S. 622, 626 (1951). This implicit license typically permits the visitor to approach the home by the front path, knock promptly, wait briefly to be received, and then (absent invitation to linger longer) leave. Complying with the terms of that traditional invitation does not require fine-grained legal knowledge; it is generally managed without incident by the Nation's Girl Scouts and trick-or-treaters.² Thus, a police officer not armed with a warrant may approach a home and knock, precisely because that is "no more than any private citizen might do." Kentucky v. King, 563 U. S. ___, ___ (2011) (slip op., at 16).

     But introducing a trained police dog to explore the area around the home in hopes of discovering incriminating evidence is something else. There is no customary invitation to do that. An invitation to engage in canine forensic investigation assuredly does not inhere in the very act of hanging a knocker.³ To find a visitor knocking on the door is routine (even if sometimes unwelcome); to spot that same visitor exploring the front path with a metal detector, or marching his bloodhound into the garden before saying hello and asking permission, would inspire most of us to--well, call the police. The scope of a license--express or implied--is limited not only to a particular area but also to a specific purpose. Consent at a traffic stop to an officer's checking out an anonymous tip that there is a body in the trunk does not permit the officer to rummage through the trunk for narcotics. Here, the background social norms that invite a visitor to the front door do not invite him there to conduct a search.⁴

     The State points to our decisions holding that the subjective intent of the officer is irrelevant. See Ashcroft v. al-Kidd, 563 U. S. ___ (2011); Whren v. United States, 517 U. S. 806 (1996). But those cases merely hold that a stop or search that is objectively reasonable is not vitiated by the fact that the officer's real reason for making the stop or search has nothing to do with the validating reason. Thus, the defendant will not be heard to complain that although he was speeding the officer's real reason for the stop was racial harassment. See id., at 810, 813. Here, however, the question before the court is precisely whether the officer's conduct was an objectively reasonable search. As we have described, that depends upon whether the officers had an implied license to enter the porch, which in turn depends upon the purpose for which they entered. Here, their behavior objectively reveals a purpose to conduct a search, which is not what anyone would think he had license to do.

III

     The State argues that investigation by a forensic narcotics dog by definition cannot implicate any legitimate privacy interest. The State cites for authority our decisions in United States v. Place, 462 U. S. 696 (1983), United States v. Jacobsen, 466 U. S. 109 (1984), and Illinois v. Caballes, 543 U. S. 405 (2005), which held, respectively, that canine inspection of luggage in an airport, chemical testing of a substance that had fallen from a parcel in transit, and canine inspection of an automobile during a lawful traffic stop, do not violate the "reasonable expectation of privacy" described in Katz.

     Just last Term, we considered an argument much like this. Jones held that tracking an automobile's whereabouts using a physically-mounted GPS receiver is a Fourth Amendment search. The Government argued that the Katz standard "show[ed] that no search occurred," as the defendant had "no 'reasonable expectation of privacy' " in his whereabouts on the public roads, Jones, 565 U. S., at ___ (slip op., at 5)--a proposition with at least as much support in our case law as the one the State marshals here. See, e.g., United States v. Knotts, 460 U. S. 276, 278 (1983). But because the GPS receiver had been physically mounted on the defendant's automobile (thus intruding on his "effects"), we held that tracking the vehicle's movements was a search: a person's "Fourth Amendment rights do not rise or fall with the Katz formulation." Jones, supra, at ___ (slip op., at 5). The Katz reasonable-expectations test "has been added to, not substituted for," the traditional property-based understanding of the Fourth Amendment, and so is unnecessary to consider when the government gains evidence by physically intruding on constitutionally protected areas. Jones, supra, at ___ (slip op., at 8).

     Thus, we need not decide whether the officers' investigation of Jardines' home violated his expectation of privacy under Katz. One virtue of the Fourth Amendment's property-rights baseline is that it keeps easy cases easy. That the officers learned what they learned only by physically intruding on Jardines' property to gather evidence is enough to establish that a search occurred.

     For a related reason we find irrelevant the State's argument (echoed by the dissent) that forensic dogs have been commonly used by police for centuries. This argument is apparently directed to our holding in Kyllo v. United States, 533 U. S. 27 (2001), that surveillance of the home is a search where "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." Id., at 40 (emphasis added). But the implication of that statement (inclusio unius est exclusio alterius) is that when the government uses a physical intrusion to explore details of the home (including its curtilage), the antiquity of the tools that they bring along is irrelevant.

*  *  *

     The government's use of trained police dogs to investigate the home and its immediate surroundings is a "search" within the meaning of the Fourth Amendment. The judgment of the Supreme Court of Florida is therefore affirmed.

It is so ordered.

Kagan, J., concurring

 569 U. S. ____ (2013)

No. 11-564

     Justice Kagan, with whom Justice Ginsburg and Justice Sotomayor join, concurring.

     For me, a simple analogy clinches this case--and does so on privacy as well as property grounds. A stranger comes to the front door of your home carrying super-high-powered binoculars. See ante, at 7, n. 3. He doesn't knock or say hello. Instead, he stands on the porch and uses the binoculars to peer through your windows, into your home's furthest corners. It doesn't take long (the binoculars are really very fine): In just a couple of minutes, his uncommon behavior allows him to learn details of your life you disclose to no one. Has your "visitor" trespassed on your property, exceeding the license you have granted to members of the public to, say, drop off the mail or distribute campaign flyers? Yes, he has. And has he also invaded your "reasonable expectation of privacy," by nosing into intimacies you sensibly thought protected from disclosure? Katz v. United States, 389 U. S. 347, 360 (1967) (Harlan, J., concurring). Yes, of course, he has done that too.

     That case is this case in every way that matters. Here, police officers came to Joelis Jardines' door with a super-sensitive instrument, which they deployed to detect things inside that they could not perceive unassisted. The equip-ment they used was animal, not mineral. But contra the dissent, see post, at 2 (opinion of Alito, J.) (noting the ubiquity of dogs in American households), that is of no significance in determining whether a search occurred. Detective Bartelt's dog was not your neighbor's pet, come to your porch on a leisurely stroll. As this Court discussed earlier this Term, drug-detection dogs are highly trained tools of law enforcement, geared to respond in distinctive ways to specific scents so as to convey clear and reliable information to their human partners. See Florida v. Harris, 568 U. S. ___ (2013) (slip op. at 2-3, 7-8). They are to the poodle down the street as high-powered binoculars are to a piece of plain glass. Like the binoculars, a drug-detection dog is a specialized device for discovering objects not in plain view (or plain smell). And as in the hypothetical above, that device was aimed here at a home--the most private and inviolate (or so we expect) of all the places and things the Fourth Amendment protects. Was this activity a trespass? Yes, as the Court holds to-day. Was it also an invasion of privacy? Yes, that as well.

     The Court today treats this case under a property rubric; I write separately to note that I could just as happily have decided it by looking to Jardines' privacy interests. A decision along those lines would have looked . . . well, much like this one. It would have talked about " 'the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion.' " Ante, at 4 (quoting Silverman v. United States, 365 U. S. 505, 511 (1961)). It would have insisted on maintaining the "practical value" of that right by preventing police officers from standing in an adjacent space and "trawl[ing] for evidence with impunity." Ante, at 4. It would have explained that " 'privacy expectations are most heightened' " in the home and the surrounding area. Ante, at 4-5 (quoting California v. Ciraolo, 476 U. S. 207, 213 (1986)). And it would have determined that police officers invade those shared expectations when they use trained canine assistants to reveal within the confines of a home what they could not otherwise have found there. See ante, at 6-7, and nn. 2-3.

     It is not surprising that in a case involving a search of a home, property concepts and privacy concepts should so align. The law of property "naturally enough influence[s]" our "shared social expectations" of what places should be free from governmental incursions. Georgia v. Randolph, 547 U. S. 103, 111 (2006); see Rakas v. Illinois, 439 U. S. 128, 143, n. 12 (1978). And so the sentiment "my home is my own," while originating in property law, now also denotes a common understanding--extending even beyond that law's formal protections--about an especially private sphere. Jardines' home was his property; it was also his most intimate and familiar space. The analysis proceeding from each of those facts, as today's decision reveals, runs mostly along the same path.

     I can think of only one divergence: If we had decided this case on privacy grounds, we would have realized that Kyllo v. United States, 533 U. S. 27 (2001), already resolved it.¹ The Kyllo Court held that police officers conducted a search when they used a thermal-imaging device to detect heat emanating from a private home, even though they committed no trespass. Highlighting our intention to draw both a "firm" and a "bright" line at "the entrance to the house," id., at 40, we announced the following rule:

"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." Ibid.

That "firm" and "bright" rule governs this case: The police officers here conducted a search because they used a "device . . . not in general public use" (a trained drug-detection dog) to "explore details of the home" (the presence of certain substances) that they would not otherwise have discovered without entering the premises.

     And again, the dissent's argument that the device is just a dog cannot change the equation. As Kyllo made clear, the "sense-enhancing" tool at issue may be "crude" or "sophisticated," may be old or new (drug-detection dogs actually go back not "12,000 years" or "centuries," post, at 2, 8, 12, but only a few decades), may be either smaller or bigger than a breadbox; still, "at least where (as here)" the device is not "in general public use," training it on a home violates our "minimal expectation of privacy"--an expectation "that exists, and that is acknowledged to be reasonable." 533 U. S., at 34, 36.² That does not mean the device is off-limits, as the dissent implies, see post, at 11-12; it just means police officers cannot use it to examine a home without a warrant or exigent circumstance. See Brigham City v. Stuart, 547 U. S. 398, 403-404 (2006) (describing exigencies allowing the warrantless search of a home).

     With these further thoughts, suggesting that a focus on Jardines' privacy interests would make an "easy cas[e] easy" twice over, ante, at 10, I join the Court's opinion in full.

Alito, J., dissenting

 569 U. S. ____ (2013)

No. 11-564

     Justice Alito, with whom The Chief Justice, Jus- tice Kennedy, and Justice Breyer join, dissenting.

     The Court's decision in this important Fourth Amendment case is based on a putative rule of trespass law that is nowhere to be found in the annals of Anglo-American jurisprudence.

     The law of trespass generally gives members of the public a license to use a walkway to approach the front door of a house and to remain there for a brief time. This license is not limited to persons who intend to speak to an occupant or who actually do so. (Mail carriers and persons delivering packages and flyers are examples of individuals who may lawfully approach a front door without intending to converse.) Nor is the license restricted to categories of visitors whom an occupant of the dwelling is likely to welcome; as the Court acknowledges, this license applies even to "solicitors, hawkers and peddlers of all kinds." Ante, at 6 (internal quotation marks omitted). And the license even extends to police officers who wish to gather evidence against an occupant (by asking potentially incriminating questions).

     According to the Court, however, the police officer in this case, Detective Bartelt, committed a trespass because he was accompanied during his otherwise lawful visit to the front door of respondent's house by his dog, Franky. Where is the authority evidencing such a rule? Dogs have been domesticated for about 12,000 years;¹ they were ubiquitous in both this country and Britain at the time of the adoption of the Fourth Amendment;² and their acute sense of smell has been used in law enforcement for centuries.³ Yet the Court has been unable to find a single case--from the United States or any other common-law nation--that supports the rule on which its decision is based. Thus, trespass law provides no support for the Court's holding today.

     The Court's decision is also inconsistent with the reasonable-expectations-of-privacy test that the Court adopted in Katz v. United States, 389 U. S. 347 (1967). A reasonable person understands that odors emanating from a house may be detected from locations that are open to the public, and a reasonable person will not count on the strength of those odors remaining within the range that, while detectible by a dog, cannot be smelled by a human.

     For these reasons, I would hold that no search within the meaning of the Fourth Amendment took place in this case, and I would reverse the decision below.

I

     The opinion of the Court may leave a reader with the mistaken impression that Detective Bartelt and Franky remained on respondent's property for a prolonged period of time and conducted a far-flung exploration of the front yard. See ante, at 4 ("trawl for evidence with impunity"), 7 ("marching his bloodhound into the garden"). But that is not what happened.

     Detective Bartelt and Franky approached the front door via the driveway and a paved path--the route that any visitor would customarily use⁴--and Franky was on the kind of leash that any dog owner might employ.⁵ As Franky approached the door, he started to track an airborne odor. He held his head high and began "bracketing" the area (pacing back and forth) in order to determine the strongest source of the smell. App. 95-96. Detective Bartelt knew "the minute [he] observed" this behavior that Franky had detected drugs. Id., at 95. Upon locating the odor's strongest source, Franky sat at the base of the front door, and at this point, Detective Bartelt and Franky immediately returned to their patrol car. Id., at 98.

     A critical fact that the Court omits is that, as respondent's counsel explained at oral argument, this entire process--walking down the driveway and front path to the front door, waiting for Franky to find the strongest source of the odor, and walking back to the car--took approximately a minute or two. Tr. of Oral Arg. 57-58. Thus, the amount of time that Franky and the detective remained at the front porch was even less. The Court also fails to mention that, while Detective Bartelt apparently did not personally smell the odor of marijuana coming from the house, another officer who subsequently stood on the front porch, Detective Pedraja, did notice that smell and was able to identify it. App. 81.

II

     The Court concludes that the conduct in this case was a search because Detective Bartelt exceeded the boundaries of the license to approach the house that is recognized by the law of trespass, but the Court's interpretation of the scope of that license is unfounded.

A

     It is said that members of the public may lawfully proceed along a walkway leading to the front door of a house because custom grants them a license to do so. Breard v. Alexandria, 341 U. S. 622, 626 (1951); Lakin v. Ames, 64 Mass. 198, 220 (1852); J. Bishop, Commentaries on the Non-Contract Law §823, p. 378 (1889). This rule encompasses categories of visitors whom most homeowners almost certainly wish to allow to approach their front doors--friends, relatives, mail carriers, persons making deliveries. But it also reaches categories of visitors who are less universally welcome--"solicitors," "hawkers," "peddlers," and the like. The law might attempt to draw fine lines between categories of welcome and unwelcome visitors, distinguishing, for example, between tolerable and intolerable door-to-door peddlers (Girl Scouts selling cookies versus adults selling aluminum siding) or between police officers on agreeable and disagreeable missions (gathering information about a bothersome neighbor versus asking potentially incriminating questions). But the law of trespass has not attempted such a difficult taxonomy. See Desnick v. American Broadcasting Cos., 44 F. 3d 1345, 1351 (CA7 1995) ("[C]onsent to an entry is often given legal effect even though the entrant has intentions that if known to the owner of the property would cause him for perfectly understandable and generally ethical or at least lawful reasons to revoke his consent"); cf. Skinner v. Ogallala Public School Dist., 262 Neb. 387, 402, 631 N. W. 2d 510, 525 (2001) ("[I]n order to determine if a business invitation is implied, the inquiry is not a subjective assessment of why the visitor chose to visit the premises in a particular instance"); Crown Cork & Seal Co. v. Kane, 213 Md. 152, 159, 131 A. 2d 470, 473-474 (1957) (noting that "there are many cases in which an invitation has been implied from circumstances, such as custom," and that this test is "objective in that it stresses custom and the appearance of things" as opposed to "the undisclosed intention of the visitor").

     Of course, this license has certain spatial and temporal limits. A visitor must stick to the path that is typically used to approach a front door, such as a paved walkway. A visitor cannot traipse through the garden, meander into the backyard, or take other circuitous detours that veer from the pathway that a visitor would customarily use. See, e.g., Robinson v. Virginia, 47 Va. App. 533, 549-550, 625 S. E. 2d 651, 659 (2006) (en banc); United States v. Wells, 648 F. 3d 671, 679-680 (CA8 2011) (police exceeded scope of their implied invitation when they bypassed the front door and proceeded directly to the back yard); State v. Harris, 919 S. W. 2d 619, 624 (Tenn. Crim. App. 1995) ("Any substantial and unreasonable departure from an area where the public is impliedly invited exceeds the scope of the implied invitation . . . " (internal quotation marks and brackets omitted)); 1 W. LaFave, Search and Seizure §2.3(c), p. 578 (2004) (hereinafter LaFave); id., §2.3(f), at 600-603 ("[W]hen the police come on to private property to conduct an investigation or for some other legitimate purpose and restrict their movements to places visitors could be expected to go (e.g., walkways, driveways, porches), observations made from such vantage points are not covered by the Fourth Amendment" (footnotes omitted)).

     Nor, as a general matter, may a visitor come to the front door in the middle of the night without an express invitation. See State v. Cada, 129 Idaho 224, 233, 923 P. 2d 469, 478 (App. 1996) ("Furtive intrusion late at night or in the predawn hours is not conduct that is expected from ordinary visitors. Indeed, if observed by a resident of the premises, it could be a cause for great alarm").

     Similarly, a visitor may not linger at the front door for an extended period. See 9 So. 3d 1, 11 (Fla. App. 2008) (case below) (Cope, J., concurring in part and dissenting in part) ("[T]here is no such thing as squatter's rights on a front porch. A stranger may not plop down uninvited to spend the afternoon in the front porch rocking chair, or throw down a sleeping bag to spend the night, or lurk on the front porch, looking in the windows"). The license is limited to the amount of time it would customarily take to approach the door, pause long enough to see if someone is home, and (if not expressly invited to stay longer), leave.

     As I understand the law of trespass and the scope of the implied license, a visitor who adheres to these limitations is not necessarily required to ring the doorbell, knock on the door, or attempt to speak with an occupant. For example, mail carriers, persons making deliveries, and individuals distributing flyers may leave the items they are carrying and depart without making any attempt to converse. A pedestrian or motorist looking for a particular address may walk up to a front door in order to check a house number that is hard to see from the sidewalk or road. A neighbor who knows that the residents are away may approach the door to retrieve an accumulation of newspapers that might signal to a potential burglar that the house is unoccupied.

     As the majority acknowledges, this implied license to approach the front door extends to the police. See ante, at 6. As we recognized in Kentucky v. King, 563 U. S. ___ (2011), police officers do not engage in a search when they approach the front door of a residence and seek to engage in what is termed a "knock and talk," i.e., knocking on the door and seeking to speak to an occupant for the purpose of gathering evidence. See id., at ___ (slip op., at 16) ("When law enforcement officers who are not armed with a warrant knock on a door, they do no more than any private citizen might do"). See also 1 LaFave §2.3(e), at 592 ("It is not objectionable for an officer to come upon that part of the property which has been opened to public common use" (internal quotation marks omitted)). Even when the objective of a "knock and talk" is to obtain evidence that will lead to the homeowner's arrest and prosecution, the license to approach still applies. In other words, gathering evidence--even damning evidence--is a lawful activity that falls within the scope of the license to approach. And when officers walk up to the front door of a house, they are permitted to see, hear, and smell whatever can be detected from a lawful vantage point. California v. Ciraolo, 476 U. S. 207, 213 (1986) ("The 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"); Cada, supra, at 232, 923 P. 2d, at 477 ("[P]olice officers restricting their activity to [areas to which the public is impliedly invited] are permitted the same intrusion and the same level of observation as would be expected from a reasonably respectful citizen" (internal quotation marks omitted)); 1 LaFave §§2.2(a), 2.3(c), at 450-452, 572-577.

B

     Detective Bartelt did not exceed the scope of the license to approach respondent's front door. He adhered to the customary path; he did not approach in the middle of the night; and he remained at the front door for only a very short period (less than a minute or two).

     The Court concludes that Detective Bartelt went too far because he had the "objectiv[e] . . . purpose to conduct a search." Ante, at 8 (emphasis added). What this means, I take it, is that anyone aware of what Detective Bartelt did would infer that his subjective purpose was to gather evidence. But if this is the Court's point, then a standard "knock and talk" and most other police visits would likewise constitute searches. With the exception of visits to serve warrants or civil process, police almost always approach homes with a purpose of discovering information. That is certainly the objective of a "knock and talk." The Court offers no meaningful way of distinguishing the "objective purpose" of a "knock and talk" from the "objective purpose" of Detective Bartelt's conduct here.

     The Court contends that a "knock and talk" is different because it involves talking, and "all are invited" to do that. Ante, at 7-8, n. 4 (emphasis deleted). But a police officer who approaches the front door of a house in accordance with the limitations already discussed may gather evidence by means other than talking. The officer may observe items in plain view and smell odors coming from the house. Ciraolo, supra, at 213; Cada, 129 Idaho, at 232, 923 P. 2d, at 477; 1 LaFave §§2.2(a), 2.3(c), at 450-452, 572-577. So the Court's "objective purpose" argument cannot stand.

     What the Court must fall back on, then, is the particular instrument that Detective Bartelt used to detect the odor of marijuana, namely, his dog. But in the entire body of common-law decisions, the Court has not found a single case holding that a visitor to the front door of a home commits a trespass if the visitor is accompanied by a dog on a leash. On the contrary, the common law allowed even unleashed dogs to wander on private property without committing a trespass. G. Williams, Liability for Animals 136-146 (1939); J. Ingham, A Treatise on Property in Animals Wild and Domestic and the Rights and Responsibilities Arising Therefrom 277-278 (1900). Cf. B. Markesinis & S. Deakin, Tort Law 511 (4th ed. 1999).

     The Court responds that "[i]t is not the dog that is the problem, but the behavior that here involved use of the dog." Ante, at 7, n. 3. But where is the support in the law of trespass for this proposition? Dogs' keen sense of smell has been used in law enforcement for centuries. The antiquity of this practice is evidenced by a Scottish law from 1318 that made it a crime to "disturb a tracking dog or the men coming with it for pursuing thieves or seizing malefactors." K. Brown et al., The Records of the Parliaments of Scotland to 1707, (St Andrews, 2007-2013), online at http://www.rps.ac.uk/mss/1318/9. If bringing a tracking dog to the front door of a home constituted a trespass, one would expect at least one case to have arisen during the past 800 years. But the Court has found none.

     For these reasons, the real law of trespass provides no support for the Court's holding today. While the Court claims that its reasoning has "ancient and durable roots," ante, at 4, its trespass rule is really a newly struck counterfeit.

III

     The concurring opinion attempts to provide an alternative ground for today's decision, namely, that Detective Bartelt's conduct violated respondent's reasonable expectations of privacy. But we have already rejected a very similar, if not identical argument, see Illinois v. Caballes, 543 U. S. 405, 409-410 (2005), and in any event I see no basis for concluding that the occupants of a dwelling have a reasonable expectation of privacy in odors that emanate from the dwelling and reach spots where members of the public may lawfully stand.

     It is clear that the occupant of a house has no reasonable expectation of privacy with respect to odors that can be smelled by human beings who are standing in such places. See United States v. Johns, 469 U. S. 478, 482 (1985) ("After the officers came closer and detected the distinct odor of marihuana, they had probable cause to believe that the vehicles contained contraband"); United States v. Ventresca, 380 U. S. 102, 111 (1965) (scent of fermenting mash supported probable cause for warrant); United States v. Johnston, 497 F. 2d 397, 398 (CA9 1974) (there is no "reasonable expectation of privacy from drug agents with inquisitive nostrils"). And I would not draw a line between odors that can be smelled by humans and those that are detectible only by dogs.

     Consider the situation from the point of view of the occupant of a building in which marijuana is grown or methamphetamine is manufactured. Would such an occupant reason as follows? "I know that odors may emanate from my building and that atmospheric conditions, such as the force and direction of the wind, may affect the strength of those odors when they reach a spot where members of the public may lawfully stand. I also know that some people have a much more acute sense of smell than others,⁶ and I have no idea who might be standing in one of the spots in question when the odors from my house reach that location. In addition, I know that odors coming from my building, when they reach these locations, may be strong enough to be detected by a dog. But I am confident that they will be so faint that they cannot be smelled by any human being." Such a finely tuned expectation would be entirely unrealistic, and I see no evidence that society is prepared to recognize it as reasonable.

     In an attempt to show that respondent had a reasonable expectation of privacy in the odor of marijuana wafting from his house, the concurrence argues that this case is just like Kyllo v. United States, 533 U. S. 27 (2001), which held that police officers conducted a search when they used a thermal imaging device to detect heat emanating from a house. Ante, at 3-4 (opinion of Kagan, J.). This Court, however, has already rejected the argument that the use of a drug-sniffing dog is the same as the use of a thermal imaging device. See Caballes, 543 U. S., at 409-410. The very argument now advanced by the concurrence appears in Justice Souter's Caballes dissent. See id., at 413, and n. 3. But the Court was not persuaded.

     Contrary to the interpretation propounded by the concurrence, Kyllo is best understood as a decision about the use of new technology. The Kyllo Court focused on the fact that the thermal imaging device was a form of "sense-enhancing technology" that was "not in general public use," and it expressed concern that citizens would be "at the mercy of advancing technology" if its use was not restricted. 533 U. S., at 34-35. A dog, however, is not a new form of "technology or a "device." And, as noted, the use of dogs' acute sense of smell in law enforcement dates back many centuries.

     The concurrence suggests that a Kyllo-based decision would be "much like" the actual decision of the Court, but that is simply not so. The holding of the Court is based on what the Court sees as a " 'physical intrusion of a constitutionally protected area.' " Ante, at 3 (quoting United States v. Knotts, 460 U. S. 276, 286 (1983) (Brennan, J., concurring in judgment)). As a result, it does not apply when a dog alerts while on a public sidewalk or street or in the corridor of a building to which the dog and handler have been lawfully admitted.

     The concurrence's Kyllo-based approach would have a much wider reach. When the police used the thermal imaging device in Kyllo, they were on a public street, 533 U. S., at 29, and "committed no trespass." Ante, at 3. Therefore, if a dog's nose is just like a thermal imaging device for Fourth Amendment purposes, a search would occur if a dog alerted while on a public sidewalk or in the corridor of an apartment building. And the same would be true if the dog was trained to sniff, not for marijuana, but for more dangerous quarry, such as explosives or for a violent fugitive or kidnaped child. I see no ground for hampering legitimate law enforcement in this way.

IV

     The conduct of the police officer in this case did not constitute a trespass and did not violate respondent's reasonable expectations of privacy. I would hold that this conduct was not a search, and I therefore respectfully dissent.

FOOTNOTES

Footnote 1

 At oral argument, the State and its amicus the Solicitor General argued that Jardines conceded in the lower courts that the officers had a right to be where they were. This misstates the record. Jardines conceded nothing more than the unsurprising proposition that the officers could have lawfully approached his home to knock on the front door in hopes of speaking with him. Of course, that is not what they did.

Footnote 2

 With this much, the dissent seems to agree--it would inquire into " 'the appearance of things,' " post, at 5 (opinion of Alito, J.), what is "typica[l]" for a visitor, ibid., what might cause "alarm" to a "resident of the premises," ibid., what is "expected" of "ordinary visitors," ibid., and what would be expected from a " 'reasonably respectful citizen,' " post, at 7. These are good questions. But their answers are incompatible with the dissent's outcome, which is presumably why the dissent does not even try to argue that it would be customary, usual, reasonable, respectful, ordinary, typical, nonalarming, etc., for a stranger to explore the curtilage of the home with trained drug dogs.

Footnote 3

 The dissent insists that our argument must rest upon "the particular instrument that Detective Bartelt used to detect the odor of marijuana"--the dog. Post, at 8. It is not the dog that is the problem, but the behavior that here involved use of the dog. We think a typical person would find it " 'a cause for great alarm' " (the kind of reaction the dissent quite rightly relies upon to justify its no-night-visits rule, post, at 5) to find a stranger snooping about his front porch with or without a dog. The dissent would let the police do whatever they want by way of gathering evidence so long as they stay on the base-path, to use a baseball analogy--so long as they "stick to the path that is typically used to approach a front door, such as a paved walkway." Ibid. From that vantage point they can presumably peer into the house through binoculars with impunity. That is not the law, as even the State concedes. See Tr. of Oral Arg. 6.

Footnote 4

 The dissent argues, citing King, that "gathering evidence--even damning evidence--is a lawful activity that falls within the scope of the license to approach." Post, at 7. That is a false generalization. What King establishes is that it is not a Fourth Amendment search to approach the home in order to speak with the occupant, because all are invited to do that. The mere "purpose of discovering information," post, at 8, in the course of engaging in that permitted conduct does not cause it to violate the Fourth Amendment. But no one is impliedly invited to enter the protected premises of the home in order to do nothing but conduct a search.

FOOTNOTES

Footnote 1

 The dissent claims, alternatively, that Illinois v. Caballes, 543 U. S. 405, 409-410 (2005), controls this case (or nearly does). See post, at 9, 11. But Caballes concerned a drug-detection dog's sniff of an automobile during a traffic stop. See also Florida v. Harris, 568 U. S. ___ (2013). And we have held, over and over again, that people's expectations of privacy are much lower in their cars than in their homes. See, e.g., Arizona v. Gant, 556 U. S. 332, 345 (2009); Wyoming v. Houghton, 526 U. S. 295, 303 (1999); New York v. Class, 475 U. S. 106, 115 (1986); Cardwell v. Lewis, 417 U. S. 583, 590-591 (1974) (plurality opinion).

Footnote 2

 The dissent's other principal reason for concluding that no violation of privacy occurred in this case--that police officers themselves might detect an aroma wafting from a house--works no better. If officers can smell drugs coming from a house, they can use that information; a human sniff is not a search, we can all agree. But it does not follow that a person loses his expectation of privacy in the many scents within his home that (his own nose capably tells him) are not usually detectible by humans standing outside. And indeed, Kyllo already decided as much. In response to an identical argument from the dissent in that case, see 533 U. S., at 43 (Stevens, J., dissenting) (noting that humans can sometimes detect "heat emanating from a building"), the Kyllo Court stated: "The dissent's comparison of the thermal imaging to various circumstances in which outside observers might be able to perceive, without technology, the heat of the home . . . is quite irrelevant. The fact that equivalent information could sometimes be obtained by other means does not make lawful the use of means that violate the Fourth Amendment. . . . In any event, [at the time in question,] no outside observer could have discerned the relative heat of Kyllo's home without thermal imaging." Id., at 35, n. 2.

FOOTNOTES

Footnote 1

 See, e.g., Sloane, Dogs in War, Police Work and on Patrol, 46 J. Crim. L., C. & P. S. 385 (1955-1956) (hereinafter Sloane).

Footnote 2

 M. Derr, A Dog's History of America 68-92 (2004); K. Olsen, Daily Life in 18th-Century England 32-33 (1999).

Footnote 3

 Sloane 388-389.

Footnote 4

 See App. 94; App. to Brief for Respondent 1A (depiction of respondent's home).

Footnote 5

 The Court notes that Franky was on a 6-foot leash, but such a leash is standard equipment for ordinary dog owners. See, e.g., J. Stregowski, Four Dog Leash Varieties, http://dogs.about.com/od/ toyssupplies/tp/Dog-Leashes.htm (all Internet materials as visited Mar. 21, 2013, and available in Clerk of Court's case file).

Footnote 6

 Some humans naturally have a much more acute sense of smell than others, and humans can be trained to detect and distinguish odors that could not be detected without such training. See E. Hancock, A Primer on Smell, http://www.jhu.edu/jhumag/996web/smell.html. Some individuals employed in the perfume and wine industries, for example, have an amazingly acute sense of smell. Ibid.

SUPREME COURT OF THE UNITED STATES

_________________

No. 13–9972

_________________

DENNYS RODRIGUEZ, PETITIONER v.  

 UNITED STATES   

ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF  APPEALS FOR THE EIGHTH CIRCUIT   

[April 21, 2015]  

JUSTICE GINSBURG delivered the opinion of the Court.

In Illinois v. Caballes, 543 U. S. 405 (2005), this Court held that a dog sniff conducted during a lawful traffic stop does not violate the Fourth Amendment’s proscription of unreasonable seizures. This case presents the question whether the Fourth Amendment tolerates a dog sniff conducted after completion of a traffic stop.  We hold that a police stop exceeding the time needed to handle the matter for which the stop was made violates the Constitution’s shield against unreasonable seizures.  A seizure justified only by a police-observed traffic violation, therefore, “become[s] unlawful if it is prolonged beyond the time reasonably required to complete th[e] mission” of issuing a ticket for the violation.  Id., at 407.  The Court so recognized in Caballes, and we adhere to the line drawn in that decision.

I

 Just after midnight on March 27, 2012, police officer Morgan Struble observed a Mercury Mountaineer veer slowly onto the shoulder of Nebraska State Highway 275 for one or two seconds and then jerk back onto the road.  

Nebraska law prohibits driving on highway shoulders, see Neb. Rev. Stat. §60–6,142 (2010), and on that basis, Struble pulled the Mountaineer over at 12:06 a.m. Struble is a  K–9 officer with the Valley Police Department in Nebraska, and his dog Floyd was in his patrol car that night.  Two men were in the Mountaineer: the driver, Dennys Rodriguez, and a front-seat passenger, Scott Pollman.  Struble approached the Mountaineer on the passenger’s side. After Rodriguez identified himself, Struble asked him why he had driven onto the shoulder. Rodriguez replied that he had swerved to avoid a pothole.  Struble then gathered Rodriguez’s license, registration, and proof of insurance, and asked Rodriguez to accompany him to the patrol car.  Rodriguez asked if he was required to do so, and Struble answered that he was not.  Rodriguez decided to wait in his own vehicle.

 After running a records check on Rodriguez, Struble returned to the Mountaineer. Struble asked passenger Pollman for his driver’s license and began to question him about where the two men were coming from and where they were going. Pollman replied that they had traveled to Omaha, Nebraska, to look at a Ford Mustang that was for sale and that they were returning to Norfolk, Nebraska.  Struble returned again to his patrol car, where he completed a records check on Pollman, and called for a second officer. Struble then began writing a warning ticket for Rodriguez for driving on the shoulder of the road.

 Struble returned to Rodriguez’s vehicle a third time to issue the written warning.  By 12:27 or 12:28 a.m., Struble had finished explaining the warning to Rodriguez, and had given back to Rodriguez and Pollman the documents obtained from them.  As Struble later testified, at that point, Rodriguez and Pollman “had all their documents back and a copy of the written warning.  I got all the reason[s] for the stop out of the way[,] . . . took care of all the business.”  App. 70.

 Nevertheless, Struble did not consider Rodriguez “free to leave.” Id., at 69–70. Although justification for the traffic stop was “out of the way,” id., at 70, Struble asked for permission to walk his dog around Rodriguez’s vehicle.  Rodriguez said no.  Struble then instructed Rodriguez to turn off the ignition, exit the vehicle, and stand in front of the patrol car to wait for the second officer.  Rodriguez complied. At 12:33 a.m., a deputy sheriff arrived.  Struble retrieved his dog and led him twice around the Mountaineer. The dog alerted to the presence of drugs halfway through Struble’s second pass. All told, seven or eight minutes had elapsed from the time Struble issued the written warning until the dog indicated the presence of drugs. A search of the vehicle revealed a large bag of methamphetamine.

 Rodriguez was indicted in the United States District Court for the District of Nebraska on one count of possession with intent to distribute 50 grams or more of methamphetamine, in violation of 21 U. S. C. §§841(a)(1) and (b)(1). He moved to suppress the evidence seized from his car on the ground, among others, that Struble had prolonged the traffic stop without reasonable suspicion in order to conduct the dog sniff.

 After receiving evidence, a Magistrate Judge recommended that the motion be denied.  The Magistrate Judge found no probable cause to search the vehicle independent of the dog alert.  App. 100 (apart from “information given by the dog,” “Officer Struble had [no]thing other than a rather large hunch”). He further found that no reasonable suspicion supported the detention once Struble issued the written warning.  He concluded, however, that under Eighth Circuit precedent, extension of the stop by “seven to eight minutes” for the dog sniff was only a de minimis intrusion on Rodriguez’s Fourth Amendment rights and was therefore permissible.

 The District Court adopted the Magistrate Judge’s factual findings and legal conclusions and denied Rodriguez’s motion to suppress. The court noted that, in the Eighth Circuit, “dog sniffs that occur within a short time following the completion of a traffic stop are not constitutionally prohibited if they constitute only de minimis intrusions.” App. 114 (quoting United States v. Alexander, 448 F. 3d 1014, 1016 (CA8 2006)).  The court thus agreed with the Magistrate Judge that the “7 to 10 minutes” added to the stop by the dog sniff “was not of constitutional significance.” App. 114. Impelled by that decision, Rodriguez entered a conditional guilty plea and was sentenced to five years in prison.

 The Eighth Circuit affirmed.  The “seven- or eightminute delay” in this case, the opinion noted, resembled delays that the court had previously ranked as permissible. 741 F. 3d 905, 907 (2014).  The Court of Appeals thus ruled that the delay here constituted an acceptable “de minimis intrusion on Rodriguez’s personal liberty.” Id., at 908. Given that ruling, the court declined to reach the question whether Struble had reasonable suspicion to continue Rodriguez’s detention after issuing the written warning.

 We granted certiorari to resolve a division among lower courts on the question whether police routinely may extend an otherwise-completed traffic stop, absent reasonable suspicion, in order to conduct a dog sniff.  573 U. S. ___ (2014). Compare, e.g., United States v. Morgan, 270 F. 3d 625, 632 (CA8 2001) (postcompletion delay of “well under ten minutes” permissible), with, e.g., State v. Baker, 2010 UT 18, ¶13, 229 P. 3d 650, 658 (2010) (“[W]ithout additional reasonable suspicion, the officer must allow the seized person to depart once the purpose of the stop has concluded.”).

II

 A seizure for a traffic violation justifies a police investigation of that violation.  “[A] relatively brief encounter,” a routine traffic stop is “more analogous to a so-called ‘Terry stop’ . . . than to a formal arrest.”  Knowles v. Iowa, 525 U. S. 113, 117 (1998) (quoting Berkemer v. McCarty, 468 U. S. 420, 439 (1984), in turn citing Terry v. Ohio, 392 U. S. 1 (1968)).  See also Arizona v. Johnson, 555 U. S. 323, 330 (2009).  Like a Terry stop, the tolerable duration of police inquiries in the traffic-stop context is determined by the seizure’s “mission”—to address the traffic violation that warranted the stop, Caballes, 543 U. S., at 407, and attend to related safety concerns, infra, at 6–7.  See also United States v. Sharpe, 470 U. S. 675, 685 (1985); Florida v. Royer, 460 U. S. 491, 500 (1983) (plurality opinion) (“The scope of the detention must be carefully tailored to its underlying justification.”).  Because addressing the infraction is the purpose of the stop, it may “last no longer than is necessary to effectuate th[at] purpose.” Ibid.  See also Caballes, 543 U. S., at 407.  Authority for the seizure thus ends when tasks tied to the traffic infraction are—or reasonably should have been—completed. See Sharpe, 470 U. S., at 686 (in determining the reasonable duration of a stop, “it [is] appropriate to examine whether the police diligently pursued [the] investigation”).

 Our decisions in Caballes and Johnson heed these constraints. In both cases, we concluded that the Fourth Amendment tolerated certain unrelated investigations that did not lengthen the roadside detention.  Johnson, 555 U. S., at 327–328 (questioning); Caballes, 543 U. S., at 406, 408 (dog sniff). In Caballes, however, we cautioned that a traffic stop “can become unlawful if it is prolonged beyond the time reasonably required to complete th[e] mission” of issuing a warning ticket.  543 U. S., at 407.  And we repeated that admonition in Johnson:  The seizure remains lawful only “so long as [unrelated] inquiries do not measurably extend the duration of the stop.” 555 U. S., at 333.  See also Muehler v. Mena, 544 U. S. 93, 101 (2005) (because unrelated inquiries did not “exten[d] the time [petitioner] was detained[,] . . . no additional Fourth Amendment justification . . . was required”).  An officer, in other words, may conduct certain unrelated checks during an otherwise lawful traffic stop.  But contrary to JUSTICE ALITO’s suggestion, post, at 4, n. 2, he may not do so in a way that prolongs the stop, absent the reasonable suspicion ordinarily demanded to justify detaining an individual. But see post, at 1–2 (ALITO, J., dissenting) (premising  opinion on the dissent’s own finding of “reasonable suspicion,” although the District Court reached the opposite conclusion, and the Court of Appeals declined to consider the issue).

 Beyond determining whether to issue a traffic ticket, an officer’s mission includes “ordinary inquiries incident to [the traffic] stop.”  Caballes, 543 U. S., at 408.  Typically such inquiries involve checking the driver’s license, determining whether there are outstanding warrants against the driver, and inspecting the automobile’s registration and proof of insurance.  See Delaware v. Prouse, 440 U. S. 648, 658–660 (1979).  See also 4 W. LaFave, Search and Seizure §9.3(c), pp. 507–517 (5th ed. 2012).  These checks serve the same objective as enforcement of the traffic code: ensuring that vehicles on the road are operated safely and responsibly. See Prouse, 440 U. S., at 658–659; LaFave, Search and Seizure §9.3(c), at 516 (A “warrant check makes it possible to determine whether the apparent traffic violator is wanted for one or more previous traffic offenses.”).

 A dog sniff, by contrast, is a measure aimed at “detect[ing] evidence of ordinary criminal wrongdoing.”  Indianapolis v. Edmond, 531 U. S. 32, 40–41 (2000).  See also Florida v. Jardines, 569 U. S. 1, ___–___ (2013) (slip op., at 7–8). Candidly, the Government acknowledged at oral argument that a dog sniff, unlike the routine measures just mentioned, is not an ordinary incident of a traffic stop.  See Tr. of Oral Arg. 33.  Lacking the same close connection to roadway safety as the ordinary inquiries, a dog sniff is not fairly characterized as part of the officer’s traffic mission.

 In advancing its de minimis rule, the Eighth Circuit relied heavily on our decision in Pennsylvania v. Mimms, 434 U. S. 106 (1977) (per curiam). See United States v. $404,905.00 in U. S. Currency, 182 F. 3d 643, 649 (CA8 1999).  In Mimms, we reasoned that the government’s “legitimate and weighty” interest in officer safety outweighs the “de minimis” additional intrusion of requiring a driver, already lawfully stopped, to exit the vehicle.  434 U. S., at 110–111. See also Maryland v. Wilson, 519 U. S. 408, 413–415 (1997) (passengers may be required to exit vehicle stopped for traffic violation).  The Eighth Circuit, echoed in JUSTICE THOMAS’s dissent, believed that the imposition here similarly could be offset by the Government’s “strong interest in interdicting the flow of illegal drugs along the nation’s highways.”  $404,905.00 in U. S. Currency, 182 F. 3d, at 649; see post, at 9.

 Unlike a general interest in criminal enforcement, however, the government’s officer safety interest stems from the mission of the stop itself. Traffic stops are “especially fraught with danger to police officers,” Johnson, 555 U. S., at 330 (internal quotation marks omitted), so an officer may need to take certain negligibly burdensome precautions in order to complete his mission safely.  Cf. United States v. Holt, 264 F. 3d 1215, 1221–1222 (CA10 2001) (en banc) (recognizing officer safety justification for criminal record and outstanding warrant checks), abrogated on other grounds as recognized in United States v. Stewart, 473 F. 3d 1265, 1269 (CA10 2007).  On-scene investigation into other crimes, however, detours from that mission. See supra, at 6–7. So too do safety precautions taken in order to facilitate such detours.  But cf. post, at 2–3 (ALITO, J., dissenting). Thus, even assuming that the imposition here was no more intrusive than the exit order in Mimms, the dog sniff could not be justified on the same basis.  Highway and officer safety are interests different in kind from the Government’s endeavor to detect crime in general or drug trafficking in particular.  The Government argues that an officer may “incremental[ly]” prolong a stop to conduct a dog sniff so long as the officer is reasonably diligent in pursuing the traffic-related purpose of the stop, and the overall duration of the stop remains reasonable in relation to the duration of other traffic stops involving similar circumstances.  Brief for United States 36–39.  The Government’s argument, in effect, is that by completing all traffic-related tasks expeditiously, an officer can earn bonus time to pursue an unrelated criminal investigation. See also post, at 2–5 (THOMAS,  J.,  dissenting) (embracing the Government’s argument).  The reasonableness of a seizure, however, depends on what the police in fact do.  See Knowles, 525 U. S., at 115–117. In this regard, the Government acknowledges that “an officer always has to be reasonably diligent.” Tr. of Oral Arg. 49.  How could diligence be gauged other than by noting what the officer actually did and how he did it? If an officer can complete traffic-based inquiries expeditiously, then that is the amount of “time reasonably required to complete [the stop’s] mission.”  Caballes, 543 U. S., at 407.  As we said in Caballes and reiterate today, a traffic stop “prolonged beyond” that point is “unlawful.” Ibid.  The critical question, then, is not whether the dog sniff occurs before or after the officer issues a ticket, as JUSTICE ALITO supposes, post, at 2–4, but whether conducting the sniff “prolongs”—i.e., adds time to—“the stop,” supra, at 6.

III

 The Magistrate Judge found that detention for the dog sniff in this case was not independently supported by individualized suspicion, see App. 100, and the District Court adopted the Magistrate Judge’s findings, see id., at 112–113. The Court of Appeals, however, did not review that determination.  But see post, at 1, 10–12 (THOMAS, J.,   dissenting) (resolving the issue, nevermind that the Court of Appeals left it unaddressed); post, at 1–2 (ALITO,  J.,  dissenting) (upbraiding the Court for addressing the sole issue decided by the Court of Appeals and characterizing the Court’s answer as “unnecessary” because the Court, instead, should have decided an issue the Court of Appeals did not decide). The question whether reasonable suspicion of criminal activity justified detaining Rodriguez beyond completion of the traffic infraction investigation, therefore, remains open for Eighth Circuit consideration on remand.

*  *  *

 For the reasons stated, the judgment of the United States Court of Appeals for the Eighth Circuit is vacated, and the case is remanded for further proceedings consistent with this opinion.

It is so ordered.

JUSTICE KENNEDY, dissenting.

 My join in JUSTICE THOMAS’ dissenting opinion does not extend to Part III. Although the issue discussed in that Part was argued here, the Court of Appeals has not addressed that aspect of the case in any detail.  In my view the better course would be to allow that court to do so in the first instance.

JUSTICE THOMAS, with whom JUSTICE ALITO joins, and with whom J USTICE KENNEDY joins as to all but Part III, dissenting.

 Ten years ago, we explained that “conducting a dog sniff [does] not change the character of a traffic stop that is lawful at its inception and otherwise executed in a reasonable manner.”  Illinois v. Caballes, 543 U. S. 405, 408 (2005). The only question here is whether an officer executed a stop in a reasonable manner when he waited to conduct a dog sniff until after he had given the driver a written warning and a backup unit had arrived, bringing the overall duration of the stop to 29 minutes.  Because the stop was reasonably executed, no Fourth Amendment violation occurred.  The Court’s holding to the contrary cannot be reconciled with our decision in Caballes or a number of common police practices. It was also unnecessary, as the officer possessed reasonable suspicion to continue to hold the driver to conduct the dog sniff. I respectfully dissent.

I

 The Fourth Amendment protects “[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.”  U. S. Const., Amdt. 4.  As the text indicates, and as we have repeatedly confirmed, “the ultimate touchstone of the Fourth Amendment is ‘reasonableness.’”  Brigham City v. Stuart, 547 U. S. 398, 403 (2006).  We have defined reasonableness “in objective terms by examining the totality of the circumstances,” Ohio v. Robinette, 519 U. S. 33, 39 (1996), and by considering “the traditional protections against unreasonable searches and seizures afforded by the common law at the time of the framing,” Atwater v. Lago Vista, 532 U. S. 318, 326 (2001) (internal quotation marks omitted). When traditional protections have not provided a definitive answer, our precedents have “analyzed a search or seizure in light of traditional standards of reasonableness by assessing, on the one hand, the degree to which it intrudes upon an individual’s privacy and, on the other, the degree to which it is needed for the promotion of legitimate governmental interests.”  Virginia v. Moore, 553 U. S. 164, 171 (2008) (internal quotation marks omitted).

 Although a traffic stop “constitutes a ‘seizure’ of ‘persons’ within the meaning of [the Fourth Amendment],” such a seizure is constitutionally “reasonable where the police have probable cause to believe that a traffic violation has occurred.”  Whren v. United States, 517 U. S. 806, 809–810 (1996). But “a seizure that is lawful at its inception can violate the Fourth Amendment if its manner of execution unreasonably infringes interests protected by the Constitution.” Caballes, supra, at 407.

 Because Rodriguez does not dispute that Officer Struble had probable cause to stop him, the only question is whether the stop was otherwise executed in a reasonable manner. See Brief for Appellant in No. 13–1176 (CA8), p. 4, n. 2.  I easily conclude that it was. Approximately 29 minutes passed from the time Officer Struble stopped Rodriguez until his narcotics-detection dog alerted to the presence of drugs.  That amount of time is hardly out of the ordinary for a traffic stop by a single officer of a vehicle containing multiple occupants even when no dog sniff is involved. See, e.g., United States v. Ellis, 497 F. 3d 606 (CA6 2007) (22 minutes); United States v. Barragan, 379 F. 3d 524 (CA8 2004) (approximately 30 minutes). During that time, Officer Struble conducted the ordinary activities of a traffic stop—he approached the vehicle, questioned Rodriguez about the observed violation, asked Pollman about their travel plans, ran serial warrant checks on Rodriguez and Pollman, and issued a written warning to Rodriguez. And when he decided to conduct a dog sniff, he took the precaution of calling for backup out of concern for his safety. See 741 F. 3d 905, 907 (CA8 2014); see also Pennsylvania v. Mimms, 434 U. S. 106, 110 (1977) (per curiam) (officer safety is a “legitimate and weighty” concern relevant to reasonableness).

As Caballes makes clear, the fact that Officer Struble waited until after he gave Rodriguez the warning to conduct the dog sniff does not alter this analysis.  Because “the use of a well-trained narcotics-detection dog . . . generally does not implicate legitimate privacy interests,” 543 U. S., at 409, “conducting a dog sniff would not change the character of a traffic stop that is lawful at its inception and otherwise executed in a reasonable manner,” id., at 408. The stop here was “lawful at its inception and otherwise executed in a reasonable manner.”  Ibid. As in Caballes, “conducting a dog sniff [did] not change the character of [the] traffic stop,” ibid., and thus no Fourth Amendment violation occurred.  

II

 Rather than adhere to the reasonableness requirement that we have repeatedly characterized as the “touchstone of the Fourth Amendment,” Brigham City, supra, at 403, the majority constructed a test of its own that is inconsistent with our precedents.

A  

 The majority’s rule requires a traffic stop to “en[d] when tasks tied to the traffic infraction are—or reasonably should have been—completed.”  Ante, at 5.  “If an officer can complete traffic-based inquiries expeditiously, then that is the amount of time reasonably required to complete the stop’s mission” and he may hold the individual no longer. Ante, at 8 (internal quotation marks and alterations omitted). The majority’s rule thus imposes a oneway ratchet for constitutional protection linked to the characteristics of the individual officer conducting the stop: If a driver is stopped by a particularly efficient officer, then he will be entitled to be released from the traffic stop after a shorter period of time than a driver stopped by a less efficient officer. Similarly, if a driver is stopped by an officer with access to technology that can shorten a records check, then he will be entitled to be released from the stop after a shorter period of time than an individual stopped by an officer without access to such technology.

 I “cannot accept that the search and seizure protections of the Fourth Amendment are so variable and can be made to turn upon such trivialities.” Whren, 517 U. S., at 815 (citations omitted). We have repeatedly explained that the reasonableness inquiry must not hinge on the characteristics of the individual officer conducting the seizure.  We have held, for example, that an officer’s state of mind “does not invalidate [an] action taken as long as the circumstances, viewed objectively, justify that action.”  Id., at 813 (internal quotation marks omitted). We have spurned theories that would make the Fourth Amendment “change with local law enforcement practices.”  Moore, supra, at 172. And we have rejected a rule that would require the offense establishing probable cause to be “closely related to” the offense identified by the arresting officer, as such a rule would make “the constitutionality of an arrest . . . vary from place to place and from time to time, depending on whether the arresting officer states the reason for the detention and, if so, whether he correctly identifies a general class of offense for which probable cause exists.”  Devenpeck v. Alford, 543 U. S. 146, 154 (2004) (internal quotation marks and citation omitted).  In Devenpeck, a unanimous Court explained: “An arrest made by a knowledgeable, veteran officer would be valid, whereas an arrest made by a rookie in precisely the same circumstances would not. We see no reason to ascribe to the Fourth Amendment such arbitrarily variable protection.”  Ibid.  The majority’s logic would produce similarly arbitrary results. Under its reasoning, a traffic stop made by a rookie could be executed in a reasonable manner, whereas the same traffic stop made by a knowledgeable, veteran officer in precisely the same circumstances might not, if in fact his knowledge and experience made him capable of completing the stop faster. We have long rejected interpretations of the Fourth Amendment that would produce such haphazard results, and I see no reason to depart from our consistent practice today.

B

 As if that were not enough, the majority also limits the duration of the stop to the time it takes the officer to complete a narrow category of “traffic-based inquiries.”  Ante, at 8. According to the majority, these inquiries include those that “serve the same objective as enforcement of the traffic code: ensuring that vehicles on the road are operated safely and responsibly.” Ante, at 6.  Inquiries directed to “detecting evidence of ordinary criminal wrongdoing” are not traffic-related inquiries and thus cannot count toward the overall duration of the stop.  Ibid. (internal quotation marks and alteration omitted).

 The combination of that definition of traffic-related inquiries with the majority’s officer-specific durational limit produces a result demonstrably at odds with our decision in Caballes. Caballes expressly anticipated that a traffic stop could be reasonably prolonged for officers to engage in a dog sniff. We explained that no Fourth Amendment violation had occurred in Caballes, where the “duration of the stop . . . was entirely justified by the traffic offense and the ordinary inquiries incident to such a stop,” but suggested a different result might attend a case “involving a dog sniff that occurred during an unreasonably prolonged traffic stop.”  543 U. S., at 407–408 (emphasis added).  The dividing line was whether the overall duration of the stop exceeded “the time reasonably required to complete th[e] mission,” id., at 407, not, as the majority suggests, whether the duration of the stop “in fact” exceeded the time necessary to complete the trafficrelated inquiries, ante, at 8.

 The majority’s approach draws an artificial line between dog sniffs and other common police practices.  The lower courts have routinely confirmed that warrant checks are a constitutionally permissible part of a traffic stop, see, e.g., United States v. Simmons, 172 F. 3d 775, 778 (CA11 1999); United States v. Mendez, 118 F. 3d 1426, 1429 (CA10 1997); United States v. Shabazz, 993 F. 2d 431, 437 (CA5 1993), and the majority confirms that it finds no fault in these measures, ante, at 6. Yet its reasoning suggests the opposite. Such warrant checks look more like they are directed to “detecting evidence of ordinary criminal wrongdoing” than to “ensuring that vehicles on the road are operated safely and responsibly.” Ante, at 6 (internal quotation marks and alteration omitted).  Perhaps one could argue that the existence of an outstanding warrant might make a driver less likely to operate his vehicle safely and responsibly on the road, but the same could be said about a driver in possession of contraband.  A driver confronted by the police in either case might try to flee or become violent toward the officer.  But under the majority’s analysis, a dog sniff, which is directed at uncovering that problem, is not treated as a traffic-based inquiry. Warrant checks, arguably, should fare no better.  The majority suggests that a warrant check is an ordinary inquiry incident to a traffic stop because it can be used “‘to  determine whether the apparent traffic violator is wanted for one or more previous traffic offenses.’”   Ante, at 6 (quoting 4 W. LaFave, Search and Seizure §9.3(c), p. 516 (5th ed. 2012)). But as the very treatise on which the majority relies notes, such checks are a “manifest[ation of] the ‘war on drugs’ motivation so often underlying [routine traffic] stops,” and thus are very much like the dog sniff in this case. Id., §9.3(c), at 507–508.

 Investigative questioning rests on the same basis as the dog sniff. “Asking questions is an essential part of police investigations.” Hiibel v. Sixth Judicial Dist. Court of Nev., Humboldt Cty., 542 U. S. 177, 185 (2004).  And the lower courts have routinely upheld such questioning during routine traffic stops. See, e.g., United States v. Rivera, 570 F. 3d 1009, 1013 (CA8 2009); United States v. Childs, 277 F. 3d 947, 953–954 (CA7 2002).  The majority’s reasoning appears to allow officers to engage in some questioning aimed at detecting evidence of ordinary criminal wrongdoing. Ante, at 5.  But it is hard to see how such inquiries fall within the “seizure’s ‘mission’ [of] ad- dress[ing] the traffic violation that warranted the stop,” or “attend[ing] to related safety concerns.”  Ibid.  Its reasoning appears to come down to the principle that dogs are different.

C

 On a more fundamental level, the majority’s inquiry elides the distinction between traffic stops based on probable cause and those based on reasonable suspicion.  Probable cause is the “traditional justification” for the seizure of a person.  Whren, 517 U. S., at 817 (emphasis deleted); see also Dunaway v. New York, 442 U. S. 200, 207–208 (1979).  This Court created an exception to that rule in Terry v. Ohio, 392 U. S. 1 (1968), permitting “police officers who suspect criminal activity to make limited intrusions on an individual’s personal security based on less than probable cause,” Michigan v. Summers, 452 U. S. 692, 698 (1981). Reasonable suspicion is the justification for such seizures. Prado Navarette v. California, 572 U. S. ___, ___ (2014) (slip op., at 3).

 Traffic stops can be initiated based on probable cause or reasonable suspicion.  Although the Court has commented that a routine traffic stop is “more analogous to a so-called ‘Terry stop’ than to a formal arrest,” it has rejected the notion “that a traffic stop supported by probable cause may not exceed the bounds set by the Fourth Amendment on the scope of a Terry stop.” Berkemer v. McCarty, 468 U. S. 420, 439, and n. 29 (1984) (citation omitted).  Although all traffic stops must be executed reasonably, our precedents make clear that traffic stops justified by reasonable suspicion are subject to additional limitations that those justified by probable cause are not.  A traffic stop based on reasonable suspicion, like all Terry stops, must be “justified at its inception” and “reasonably related in scope to the circumstances which justified the interference in the first place.”  Hiibel, 542 U. S., at 185 (internal quotation marks omitted).  It also “cannot continue for an excessive period of time or resemble a traditional arrest.”  Id., at 185–186 (citation omitted).  By contrast, a stop based on probable cause affords an officer considerably more leeway. In such seizures, an officer may engage in a warrantless arrest of the driver, Atwater, 532 U. S., at 354, a warrantless search incident to arrest of the driver, Riley v. California, 573 U. S. ___, ___ (2014) (slip op., at 5), and a warrantless search incident to arrest of the vehicle if it is reasonable to believe evidence relevant to the crime of arrest might be found there, Arizona v. Gant, 556 U. S. 332, 335 (2009).

 The majority casually tosses this distinction aside.  It asserts that the traffic stop in this case, which was undisputedly initiated on the basis of probable cause, can last no longer than is in fact necessary to effectuate the mission of the stop.  Ante, at 8. And, it assumes that the mission of the stop was merely to write a traffic ticket, rather than to consider making a custodial arrest.  Ante, at 5. In support of that durational requirement, it relies primarily on cases involving Terry stops. See ante, at 5–7 (citing Arizona v. Johnson, 555 U. S. 323 (2009) (analyzing “stop and frisk” of passenger in a vehicle temporarily seized for a traffic violation); United States v. Sharpe, 470 U. S. 675 (1985) (analyzing seizure of individuals based on suspicion of marijuana trafficking); Florida v. Royer, 460 U. S. 491 (1983) (plurality opinion) (analyzing seizure of man walking through airport on suspicion of narcotics activity)).

The only case involving a traffic stop based on probable cause that the majority cites for its rule is Caballes. But, that decision provides no support for today’s restructuring of our Fourth Amendment jurisprudence.  In Caballes, the Court made clear that, in the context of a traffic stop supported by probable cause, “a dog sniff would not change the character of a traffic stop that is lawful at its inception and otherwise executed in a reasonable manner.”  543 U. S., at 408.  To be sure, the dissent in Caballes would have “appl[ied] Terry’s reasonable-relation test . . . to determine whether the canine sniff impermissibly expanded the scope of the initially valid seizure of Caballes.”  Id., at 420 (GINSBURG, J., dissenting).  But even it conceded that the Caballes majority had “implicitly [rejected] the application of Terry to a traffic stop converted, by calling in a dog, to a drug search.” Id., at 421.

 By strictly limiting the tasks that define the durational scope of the traffic stop, the majority accomplishes today what the Caballes dissent could not: strictly limiting the scope of an officer’s activities during a traffic stop justified by probable cause. In doing so, it renders the difference between probable cause and reasonable suspicion virtually meaningless in this context.  That shift is supported neither by the Fourth Amendment nor by our precedents interpreting it. And, it results in a constitutional framework that lacks predictability.  Had Officer Struble ar- rested, handcuffed, and taken Rodriguez to the police station for his traffic violation, he would have complied with the Fourth Amendment.  See Atwater, supra, at 354– 355. But because he made Rodriguez wait for seven or eight extra minutes until a dog arrived, he evidently committed a constitutional violation.  Such a view of the Fourth Amendment makes little sense.

III

 Today’s revision of our Fourth Amendment jurisprudence was also entirely unnecessary.  Rodriguez suffered no Fourth Amendment violation here for an entirely independent reason: Officer Struble had reasonable suspicion to continue to hold him for investigative purposes.  Our precedents make clear that the Fourth Amendment permits an officer to conduct an investigative traffic stop when that officer has “a particularized and objective basis for suspecting the particular person stopped of criminal activity.”  Prado Navarette, 572 U. S., at ___ (slip op., at 3) (internal quotation marks omitted). Reasonable suspicion is determined by looking at “the whole picture,” ibid., taking into account “the factual and practical considerations of everyday life on which reasonable and prudent men, not legal technicians, act,” Ornelas v. United States, 517 U. S. 690, 695 (1996) (internal quotation marks omitted).

 Officer Struble testified that he first became suspicious that Rodriguez was engaged in criminal activity for a number of reasons. When he approached the vehicle, he  smelled an “overwhelming odor of air freshener coming from the vehicle,” which is, in his experience, “a common attempt to conceal an odor that [people] don’t want . . . to be smelled by the police.”  App. 20–21.  He also observed, upon approaching the front window on the passenger side of the vehicle, that Rodriguez’s passenger, Scott Pollman, appeared nervous.  Pollman pulled his hat down low, puffed nervously on a cigarette, and refused to make eye contact with him.  The officer thought he was “more nervous than your typical passenger” who “do[esn’t] have anything to worry about because [t]hey didn’t commit a [traffic] violation.”  Id., at 34.

 Officer Struble’s interactions with the vehicle’s occupants only increased his suspicions.  When he asked Rod- riguez why he had driven onto the shoulder, Rodriguez claimed that he swerved to avoid a pothole.  But that story could not be squared with Officer Struble’s observation of the vehicle slowly driving off the road before being jerked back onto it. And when Officer Struble asked Pollman where they were coming from and where they were going, Pollman told him they were traveling from Omaha, Nebraska, back to Norfolk, Nebraska, after looking at a vehicle they were considering purchasing.  Pollman told the officer that he had neither seen pictures of the vehicle nor confirmed title before the trip.  As Officer Struble explained, it “seemed suspicious” to him “to drive . . . approximately two hours . . . late at night to see a vehicle sight unseen to possibly buy it,” id., at 26, and to go from Norfolk to Omaha to look at it because “[u]sually people leave Omaha to go get vehicles, not the other way around” due to higher Omaha taxes, id., at 65.

 These facts, taken together, easily meet our standard for reasonable suspicion.  “[N]ervous, evasive behavior is a pertinent factor in determining reasonable suspicion,” Illinois v. Wardlow, 528 U. S. 119, 124 (2000), and both vehicle occupants were engaged in such conduct.  The officer also recognized heavy use of air freshener, which, in his experience, indicated the presence of contraband in the vehicle. “[C]ommonsense judgments and inferences about human behavior” further support the officer’s conclusion that Pollman’s story about their trip was likely a cover story for illegal activity. Id., at 125. Taking into account all the relevant facts, Officer Struble possessed reasonable suspicion of criminal activity to conduct the dog sniff.  Rodriguez contends that reasonable suspicion cannot exist because each of the actions giving rise to the officer’s suspicions could be entirely innocent, but our cases easily dispose of that argument. Acts that, by themselves, might be innocent can, when taken together, give rise to reasonable suspicion.  United States v. Arvizu, 534 U. S. 266, 274–275 (2002). Terry is a classic example, as it involved two individuals repeatedly walking back and forth, looking into a store window, and conferring with one another as well as with a third man.  392 U. S., at 6. The Court reasoned that this “series of acts, each of them perhaps innocent in itself, . . . together warranted further investigation,” id., at 22, and it has reiterated that analysis in a number of cases, see, e.g., Arvizu, supra, at 277; United States v. Sokolow, 490 U. S. 1, 9–10 (1989).  This one is no different.

*  *  *

 I would conclude that the police did not violate the Fourth Amendment here.  Officer Struble possessed probable cause to stop Rodriguez for driving on the shoulder, and he executed the subsequent stop in a reasonable manner. Our decision in Caballes requires no more. The majority’s holding to the contrary is irreconcilable with Caballes and a number of other routine police practices, distorts the distinction between traffic stops justified by probable cause and those justified by reasonable suspicion, and abandons reasonableness as the touchstone of the Fourth Amendment.  I respectfully dissent.

JUSTICE ALITO, dissenting.

 This is an unnecessary,^[1] impractical, and arbitrary decision. It addresses a purely hypothetical question: whether the traffic stop in this case would be unreasonable if the police officer, prior to leading a drug-sniffing dog  around the exterior of petitioner’s car, did not already have reasonable suspicion that the car contained drugs.  In fact, however, the police officer did have reasonable suspicion, and, as a result, the officer was justified in detaining the occupants for the short period of time (seven or eight minutes) that is at issue.

 The relevant facts are not in dispute. Officer Struble, who made the stop, was the only witness at the suppression hearing, and his testimony about what happened was not challenged. Defense counsel argued that the facts recounted by Officer Struble were insufficient to establish reasonable suspicion, but defense counsel did not dispute those facts or attack the officer’s credibility. Similarly, the Magistrate Judge who conducted the hearing did not question the officer’s credibility.  And as JUSTICE THOMAS’s opinion shows, the facts recounted by Officer Struble “easily meet our standard for reasonable suspicion.”  Ante, at 11 (dissenting opinion); see also, e.g., United  

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2

States v. Carpenter, 462 F. 3d 981, 986–987 (CA8 2006) (finding reasonable suspicion for a dog sniff based on implausible travel plans and nervous conduct); United States v. Ludwig, 641 F. 3d 1243, 1248–1250 (CA10 2011) (finding reasonable suspicion for a dog sniff where, among other things, the officer smelled “strong masking odors,” the defendant’s “account of his travel was suspect,” and the defendant “was exceptionally nervous throughout his encounter”).

 Not only does the Court reach out to decide a question not really presented by the facts in this case, but the Court’s answer to that question is arbitrary. The Court refuses to address the real Fourth Amendment question: whether the stop was unreasonably prolonged.  Instead, the Court latches onto the fact that Officer Struble delivered the warning prior to the dog sniff and proclaims that the authority to detain based on a traffic stop ends when a citation or warning is handed over to the driver.  The Court thus holds that the Fourth Amendment was vio- lated, not because of the length of the stop, but simply be- cause of the sequence in which Officer Struble chose to perform his tasks.

 This holding is not only arbitrary; it is perverse since Officer Struble chose that sequence for the purpose of protecting his own safety and possibly the safety of others.  See App. 71–72.  Without prolonging the stop, Officer Struble could have conducted the dog sniff while one of the tasks that the Court regards as properly part of the traffic stop was still in progress, but that sequence would have entailed unnecessary risk.  At approximately 12:19 a.m., after collecting Pollman’s driver’s license, Officer Struble did two things. He called in the information needed to do a records check on Pollman (a step that the Court recognizes was properly part of the traffic stop), and he requested that another officer report to the scene.  Officer Struble had decided to perform a dog sniff but did not want to do that without another officer present. When occupants of a vehicle who know that their vehicle contains a large amount of illegal drugs see that a drugsniffing dog has alerted for the presence of drugs, they will almost certainly realize that the police will then proceed to search the vehicle, discover the drugs, and make arrests.  Thus, it is reasonable for an officer to believe that an alert will increase the risk that the occupants of the vehicle will attempt to flee or perhaps even attack the officer.  See, e.g., United States v. Dawdy, 46 F. 3d 1427, 1429 (CA8 1995) (recounting scuffle between officer and defendant after drugs were discovered).

 In this case, Officer Struble was concerned that he was outnumbered at the scene, and he therefore called for backup and waited for the arrival of another officer before conducting the sniff.  As a result, the sniff was not completed until seven or eight minutes after he delivered the warning. But Officer Struble could have proceeded with the dog sniff while he was waiting for the results of the records check on Pollman and before the arrival of the second officer. The drug-sniffing dog was present in Officer Struble’s car.  If he had chosen that riskier sequence of events, the dog sniff would have been completed before the point in time when, according to the Court’s analysis, the authority to detain for the traffic stop ended.  Thus, an action that would have been lawful had the officer made the unreasonable decision to risk his life became un- lawful when the officer made the reasonable decision to wait  a few minutes for backup.  Officer Struble’s error— apparently—was following prudent procedures motivated by legitimate safety concerns. The Court’s holding therefore makes no practical sense. And nothing in the Fourth Amendment, which speaks of reasonableness, compels this arbitrary line.

 The rule that the Court adopts will do little good going forward.^[2]  It is unlikely to have any appreciable effect on the length of future traffic stops. Most officers will learn the prescribed sequence of events even if they cannot fathom the reason for that requirement.  (I would love to be the proverbial fly on the wall when police instructors teach this rule to officers who make traffic stops.)  For these reasons and those set out in JUSTICE THOMAS’s opinion, I respectfully dissent.  

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[1] See Brief in Opposition 11–14.

[2] It is important to note that the Court’s decision does not affect procedures routinely carried out during traffic stops, including “checking the driver’s license, determining whether there are outstanding warrants against the driver, and inspecting the automobile’s registration and proof of insurance.” Ante, at 6. And the Court reaffirms that police “may conduct certain unrelated checks during an otherwise lawful traffic stop.” Ibid.  Thus, it remains true that police may ask questions aimed at uncovering other criminal conduct and may order occupants out of their car during a valid stop.  See Arizona v. Johnson, 555 U. S. 323, 333 (2009); Maryland v. Wilson, 519 U. S. 408, 414–415 (1997); Pennsylvania v. Mimms, 434 U. S. 106, 111 (1977) (per curiam).