The Fourth Amendment prohibits police from entering the curtilage of a home to search a vehicle without a warrant, the U.S. Supreme Court held May 29 in Collins v. Virginia.
The Court rejected the claim that the “automobile exception” justified such a search.
Police were investigating Ryan Collins for possession of a stolen motorcycle.  They went to his girlfriend’s house, where Collins stayed a few nights per week, and saw a motorcycle up the driveway and under a tarp.
Acting without a search warrant, police walked up the driveway, pulled off the tarp, and confirmed the motorcycle was stolen.  They then arrested Collins for receiving stolen property.
Collins moved to suppress.  He contended the search of the motorcycle violated the Fourth Amendment because police had trespassed on the curtilage of the house to conduct their investigation without a warrant.
The Virginia courts ultimately denied suppression on grounds that the warrantless search was justified under the “automobile exception,” because police had probable cause to believe the motorcycle was stolen.
Automobile exception not apply
The Supreme Court, in an 8-1 opinion, reversed. 
The “automobile exception” does not justify the invasion of the house’s curtilage, the Court ruled.  This was an “easy case” by imagining slightly different facts. 
“Imagine a motorcycle parked inside the living room of a house, visible through a window to the passerby on the street?” the Court said.  “Can the officer, acting without a warrant, enter the house to search the motorcycle and confirm whether it is the right one?  Surely not.”
“[T]he scope of the automobile exception extends no further than the automobile itself,” the Court said.  “Nothing in our case law, however, suggests that the automobile exception gives an officer the right to enter a home or its curtilage to access a vehicle without a warrant.”
The Court noted that it had already refused to expand other Fourth Amendment exceptions to permit warrantless entry into a home.  For example, the plain view exception does not permit warrantless trespass into a home.  And police need a warrant to arrest someone in a home, even when they have probable cause.
Justice Thomas says exclusionary should not be required
Justice Thomas concurred.  He agreed that the search violated the Fourth Amendment, but wrote separately to say that the Court did not have the authority to impose the exclusionary rule on the States.
When the Fourth Amendment was adopted, the remedy for unconstitutional searches and seizures was tort suits, he said.  The exclusionary rule did not arise until the twentieth century, and is not constitutionally required.
He urged the Court to revisit whether the exclusionary rule is mandatory on the States.
Dissenting opinion
Justice Alito dissented.  He said Fourth Amendment prohibits only “unreasonable” searches, and “[w]hat the police did in this case was entirely reasonable.”
He said that whether a search is reasonable turns on the degree on the intrusion of privacy.
“[C]ontrary to the opinion of the Court, an affirmance in this case would not mean that officers could perform a warrantless search if a motorcycle were located inside a house,” he said.  “In that situation, the intrusion on privacy would be far greater than in the present case, where the real effect, if any, is negligible.”