In the 1920 case of Amos v. United States, the U.S Supreme Court upheld a lower court's decision to convict and sentence William Amos for violating Prohibition laws. The defense argued that evidence used against him was obtained illegally because it was seized during an unwarranted search of his home by federal agents. However, the Supreme Court ruled in favor of the government stating that Fourth Amendment protections against unreasonable searches and seizures did not apply to federal officers as they were not specifically mentioned in this amendment. This ruling effectively allowed federal law enforcement agencies to conduct warrantless searches until it was overturned by Weeks v. United States (1914) which established what is now known as "the exclusionary rule," prohibiting use of evidence obtained through illegal searches and seizures.

In the dissenting opinion for Amos v. United States, Justice Oliver Wendell Holmes Jr. argued that the defendant's Fourth Amendment rights were violated when evidence was seized from his home without a warrant or probable cause. He contended that this seizure constituted an unreasonable search and seizure, which is explicitly prohibited by the Constitution. The majority ruling held that because the defendant had not objected to the search at trial, he could not raise this issue on appeal; however, Justice Holmes disagreed with this interpretation of procedural rules and believed it should not be used to excuse constitutional violations. Furthermore, he expressed concern about allowing law enforcement officers too much discretion in conducting searches without warrants or probable cause as it might lead to abuses of power and infringements on individual liberties.