In the case of South Dakota v. Opperman, 1975, the U.S. Supreme Court ruled in favor of law enforcement's right to conduct inventory searches without a warrant following an arrest or impoundment of a vehicle. The case arose when police in Vermillion, South Dakota impounded an illegally parked car and discovered marijuana during their routine inventory search at the station house lot. The owner was subsequently charged with possession but argued that his Fourth Amendment rights had been violated as there was no warrant for the search nor any probable cause to suspect criminal activity beyond illegal parking. However, by a vote of 6-3, the court held that such searches were not unreasonable under Fourth Amendment standards because they served three distinct governmental interests: protection of public safety; protection against claims or disputes over lost property; and deterrence against false claims about what might have been inside an automobile at time it is taken into custody.

In the dissenting opinion for South Dakota v. Opperman, Justice Marshall argued that the majority's decision to allow inventory searches without a warrant was an erosion of Fourth Amendment protections against unreasonable search and seizure. He contended that such searches should only be allowed when there is probable cause or exigent circumstances, neither of which were present in this case. The police had no reason to believe any evidence would be lost if they did not immediately search the car; instead, they could have secured it and obtained a warrant before conducting their search. Furthermore, he disagreed with the majority’s view that inventory searches are merely caretaking functions rather than investigative ones – arguing that even if some may serve both purposes simultaneously, this does not justify bypassing constitutional requirements for obtaining warrants based on probable cause.