In the United States v. Ross case of 1981, the U.S. Supreme Court ruled that law enforcement officers who have legally stopped a vehicle and have probable cause to believe there is contraband inside may search the entire vehicle, including all containers within it that could potentially conceal the object of their search without obtaining a warrant first. The decision expanded upon previous rulings in Carroll v. United States (1925) which allowed for warrantless searches of vehicles but did not explicitly extend this principle to closed packages or compartments found within those vehicles. In this case, police received an anonymous tip about Albert Ross selling narcotics from his car trunk; they subsequently searched his car and discovered heroin in a brown paper bag inside a zippered leather pouch in his trunk after stopping him on two separate occasions.

In the dissenting opinion for United States v. Ross, Justice Brennan argued that the majority's decision to allow warrantless searches of closed containers within vehicles contradicted previous rulings and violated Fourth Amendment protections against unreasonable searches. He contended that there was no justification for treating a motor vehicle differently from a home or office in terms of privacy expectations. Furthermore, he disagreed with the majority's assertion that an individual has less expectation of privacy in their car than they do in their home or office; rather, he believed this should be determined on a case-by-case basis considering factors such as location and nature of use. He also criticized the court’s reliance on Carroll v. United States (1925) which allowed warrantless automobile searches based on probable cause but did not address closed containers inside cars specifically.