Johnson v. United States
Citation: 333 U.S. 10 (1948)
Facts
Federal narcotics agents detected the smell of opium coming from a hotel room. Without a warrant, they knocked, demanded entry, and searched the room after Johnson opened the door. The agents had no exigent circumstances — the occupant was not fleeing and there was no risk of evidence destruction.
Issue
When police have probable cause to believe a crime is being committed in a hotel room, may they search without first obtaining a warrant?
Holding
No. The search violated the Fourth Amendment. The smell of opium established probable cause, but that alone does not justify a warrantless entry into a private room. The officers had sufficient time to obtain a warrant.
Rule
Warrant preference rule: When officers have probable cause but no exigent circumstances, they must obtain a warrant before searching a private dwelling or hotel room. The requirement of prior judicial approval is central to the Fourth Amendment’s protection. Probable cause without a warrant is insufficient absent an applicable exception.
Neutral magistrate: The warrant requirement ensures that probable cause is assessed by a neutral and detached magistrate, not by police officers in the heat of investigation who are “engaged in the often competitive enterprise of ferreting out crime.”
Significance
- Famous for the “neutral and detached magistrate” language — one of the most cited expressions of the warrant requirement’s purpose
- Reinforces that probable cause alone does not create a right to search; a warrant is required absent an exception
- Forms part of the foundational cases on the warrant requirement, taught alongside Katz and Illinois v. Gates