An
exigent circumstance, in the
criminal procedure law of the
United States, allows law enforcement, under certain circumstances, to enter a structure without a
search warrant or, if they have a "
knock and announce" warrant, without knocking and waiting for refusal. It must be a situation where people are in imminent danger,
evidence faces imminent destruction, or a
suspect's imminent escape. Once entry is obtained, the
plain view doctrine applies, allowing the seizure of any evidence or contraband discovered in the course of actions consequent upon the exigent circumstances.