Automobile searches constitute a recognized exception to the fourth amendment's requirement of a search warrant. When police have probable cause to believe an automobile is transporting contraband, they may, under carroll v. united states (1925) and brinegar v. united states (1941), conduct a warrantless search of the vehicle lest it disappear before a warrant can be obtained. Under chambers v. maroney (1970) the search may be delayed until the vehicle has been removed to a police station, though the emergency that attends a search on the road has dissipated. The rules governing automobile searches apply also to mobile homes, according to California v. Carney (1985).
Early cases stressed the vehicle's mobility as justification for a warrantless search, but most recent cases have also emphasized an individual's reduced expectation of privacy in an automobile. In contrast to a dwelling, an automobile usually does not serve as a repository of one's belongings; its interior is plainly visible from the outside; and it is commonly stopped by police enforcing inspection and licensing laws. Nonetheless, as the court held in coolidge v. new hampshire (1971), a car parked on private property may not be searched without a warrant.
Systematic stopping of automobiles at checkpoints for license and registration checks is permitted, but under the Court's decision in Delaware v. Prouse (1979), their random stopping is forbidden absent suspicious circumstances. And under Opperman v. South Dakota (1976) a lawfully impounded vehicle may be subjected to a warrantless inventory search to safeguard the owner's possessions and protect police from false property claims.
The scope of the warrantless automobile search is as broad as one a magistrate could authorize with a warrant. As the Court held in united states v. ross (1982), the search may encompass "every part of the vehicle that might contain the object of the search," including the trunk, glove compartment, and closed containers. Furthermore, the Court has applied lenient standards in automobile search cases as to the evidence needed to establish probable cause. Justice john marshall harlan, dissenting in united states v. harris (1971), accurately remarked that the problem of automobile searches "has typically been treated as sui generis by this Court."
Jacob W. Landynski
Landynski, Jacob W. 1971 The Supreme Court's Search for Fourth Amendment Standards: The Warrantless Search. Connecticut Bar Journal 45:30–39.