On March 26, 2013, the U.S. Supreme Court decided Florida v. Jardines, No. 11-564, holding that using a drug-sniffing dog on the front porch of a home to investigate its contents is a "search" within the meaning of the Fourth Amendment.

The Fourth Amendment provides 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." In 2006, police took a drug-sniffing dog to Jardines' front porch where it detected a drug odor. Based on the dog's behavior, the police received a warrant to search Jardines' home, where they discovered marijuana plants. Jardines was charged with cannabis trafficking. At trial, the court granted Jardines' motion to suppress the marijuana plants. The Florida Supreme Court affirmed the trial court's decision, finding the canine investigation an unreasonable Fourth Amendment search unsupported by probable cause.

The Supreme Court affirmed, holding that the officers' use of the drug-sniffing dog was a search within the meaning of the Fourth Amendment. The Court began with the "simple baseline" that obtaining information by physically intruding on "persons, houses, papers, or effects" is a search under the Fourth Amendment's original meaning. It further noted that the area "immediately surrounding and associated with the home" (known as the curtilage) is regarded, under longstanding principles, as part of the home itself. Describing the front porch as the "classic exemplar of an area adjacent to the home," the Court concluded that the officers had intruded on an area protected by the Fourth Amendment. The Court also found the officers' entry not explicitly or implicitly invited. It reasoned that a warrantless police officer may approach a home and knock because any citizen might do so; there is an implicit license. But "social norms that invite a visitor to the front door do not invite [the visitor] there to conduct a search." Finally, the Court found it unnecessary to determine whether the officers violated Jardines' reasonable expectation of privacy; rather, the officers' physical intrusion onto the porch established that a search had occurred.

Justice Scalia delivered the opinion of the Court, in which Justices Thomas, Ginsburg, Sotomayor and Kagan joined. Justice Kagan filed a concurring opinion, in which Justices Ginsburg and Sotomayor joined. Justice Alito filed a dissenting opinion, in which Chief Justice Roberts and Justices Kennedy and Breyer joined.

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