A no-knock warrant is a search warrant authorizing police officers to enter certain premises without first knocking and announcing their presence or purpose prior to entering the premises. Such warrants are issued where an entry pursuant to the knock-and-announce rule (ie. an announcement prior to entry) would lead to the destruction of the objects for which the police are searching or would compromise the safety of the police or another individual. The requirement that announcing police presence would result in destruction of objects or compromise safety is judged by a reasonable suspicion standard.
The Department of Justice, in a legal memo on the authority of federal judges and magistrates to issue no-knock warrants, recognized that "Although officers need not take affirmative steps to make an independent re-verification of the circumstances already recognized by a magistrate in issuing a no-knock warrant, such a warrant does not entitle officers to disregard reliable information clearly negating the existence of exigent circumstances when they actually receive such information before execution of the warrant."
No-knock warrants have become both more common and increasingly controversial in recent years, resulting in bans in some states on issuing no-knock warrants. However, federal law enforcement officials may still use no-knock warrants in those states and municipalities that ban the practice.
[Last updated in July of 2023 by the Wex Definitions Team]