A warrant is the ordinary model, not an absolute requirement for every reasonable search. Voluntary consent, emergency aid, hot pursuit, imminent destruction of evidence, certain automobile searches, and searches incident to lawful arrest are recognized exceptions with their own limits. If a homeowner consents only to a search of the living room, officers cannot treat that permission as authority to open a locked box in the bedroom. If officers hear cries for help inside, the emergency may justify entry without waiting for a warrant.

In Case v. Montana (2026), the Court stated the emergency-aid rule more precisely: officers may enter a home when they have an objectively reasonable basis for believing that an occupant is seriously injured or imminently threatened with serious injury. Because emergency aid is noninvestigatory, the Court declined to replace that standard with either probable cause or reasonable suspicion. The common mistake is to say that probable cause by itself always authorizes a warrantless search. Probable cause can support a warrant, but officials still need the warrant unless an exception applies. In the criminal-process sequence, first ask whether a search occurred, then whether a valid warrant or exception made it reasonable, and only afterward whether unlawfully obtained evidence should be excluded.

Video lesson: Due Process of Law: Crash Course Government and Politics #28