term:

Knock And Announce Rule

knock and announce rule n

: a rule of criminal procedure requiring that police announce their authority and purpose before entering a premises in execution of a search or arrest warrant unless special circumstances (as risk of harm to the police) warrant unannounced or forcible entry compare exigent circumstances no-knock search warrant at warrant

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.