In the 1942 case Johnson v. United States, the Supreme Court ruled that law enforcement officers must have a warrant to enter and search a private residence unless there are exigent circumstances present. The case arose when Seattle police officers smelled opium coming from an apartment, knocked on the door, and forced their way in after receiving no response. They arrested four people inside for violating narcotics laws and seized several pieces of drug paraphernalia as evidence. One of those arrested was Ms. Johnson who appealed her conviction arguing that it violated her Fourth Amendment rights against unreasonable searches and seizures because the police did not have a warrant to enter her home. The Supreme Court agreed with Ms.Johnson's argument stating that "a man's house is his castle" meaning individuals should be free from arbitrary intrusion by government officials into their homes without proper legal authority such as a search warrant or probable cause under exigent circumstances like imminent danger or destruction of evidence.

In the dissenting opinion for Johnson v. United States, Justice Frank Murphy argued that the majority's decision to uphold a warrantless search of a hotel room was an erosion of Fourth Amendment protections against unreasonable searches and seizures. He contended that law enforcement should have obtained a warrant before conducting the search, as there was ample time and opportunity to do so without jeopardizing public safety or risking loss of evidence. In his view, allowing such searches based on mere suspicion or belief undermines citizens' constitutional rights and opens up potential for abuse by police powers. The absence of exigent circumstances in this case made it unjustifiable not to seek a warrant first; thus he disagreed with the Court's ruling which upheld Johnson’s conviction based on evidence gathered from this unwarranted intrusion.