Justice Scalia wrote that the use of the dog at the entry to a home was a search, and the officers’ entry was not explicitly or implicitly invited:
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 “un- doubtedly occurred.....”
.... 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. While law enforcement officers need not “shield their eyes” when passing by the home “on public thoroughfares,” ... an officer’s leave to gather information is sharply circumscribed when he steps off those thoroughfares and enters the Fourth Amendment’s protected areas.
....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.
In a concurring opinion, Justices Kagan, Ginsburg and Sotomayor wrote that they would have invalidated the search based on both the Fourth Amendment and on privacy grounds. Justice Thomas agreed with Scalia.
Justice Alito dissented, joined by Justices Breyer, Kennedy and Roberts. They believe the use of the dog without a warrant at the entry of a home is not a search, or a trespass and the owner had no reasonable expectation of privacy from the dog sniff.
Background on the case is here.
Just two months ago, in Florida v. Harris, the court upheld a dog sniff challenge on reliability grounds.
