South Dakota v. Opperman

Police in Vermillion, South Dakota towed an illegally parked car, and at the impound lot, an officer noticed a watch and other property visible inside; the officer unlocked the car and performed a standard inventory search using a routine form, discovering marijuana in the unlocked glove compartment. Opperman (defendant) was arrested when he came to claim his property, and after his motion to suppress the inventory-search evidence was denied, he was convicted and fined; the South Dakota Supreme Court reversed, finding a Fourth Amendment violation, and the U.S. Supreme Court granted certiorari.