Scalia, J.
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.
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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.
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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.
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. . . 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.
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“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. [Footnote omitted.] 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. [Footnote omitted.] 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. [Footnote omitted.]
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. . . [W]e 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.
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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.
THOMAS, GINSBURG, SOTOMAYOR, and KAGAN, JJ., joined. KAGAN, J., filed a concurring opinion, in which GINSBURG and SOTOMAYOR, JJ., joined. ALITO, J., filed a dissenting opinion, in which ROBERTS, C. J., and KENNEDY and BREYER, JJ., joined.