In United States v. Chadwick et al., the U.S. Supreme Court ruled that without a warrant, law enforcement officers cannot search personal luggage and other closed containers unless they have probable cause to believe it contains contraband or evidence of illegal activity and there are exigent circumstances necessitating immediate action. The case involved federal agents who had arrested defendants for transporting marijuana in a footlocker placed in their car's trunk. Although the agents had ample opportunity to obtain a warrant before opening the footlocker, they chose not to do so. The court held that this violated Fourth Amendment protections against unreasonable searches and seizures because once law enforcement has seized such an item from an individual’s immediate possession, there is no longer any danger that he might gain access to its contents.

In the dissenting opinion for United States v. Chadwick, Justice Blackmun argued that the majority's decision was an unnecessary and potentially harmful restriction on law enforcement procedures. He contended that there were significant practical difficulties in distinguishing between personal luggage and other types of containers or packages, which could lead to confusion and inconsistency in police practices. Furthermore, he suggested that this ruling might encourage criminals to transport illegal goods in personal luggage as a way to evade searches by law enforcement officers. In his view, it would be more reasonable and effective to allow warrantless searches of any property associated with a person under arrest if there is probable cause to believe it contains evidence of crime.