In law enforcement, a knock and talk is an investigative technique where one or more police officers approaches a private residence, knocks on the door, and requests consent from the owner to search the residence.[1] This strategy is often utilised when criminal activity is suspected, but there is not sufficient evidence to obtain a search warrant.
The legality of the knock and talk procedure has been carefully scrutinized and reviewed by American courts at the state and federal level.[1][2][3] Rulings in both the Ninth Circuit case United States v. Cormier[1] and Seventh Circuit case United States v. Jerez[1] have held that evidence obtained from a consensual search following a knock and talk is admissible, but only if the knock and talk is not conducted in a coercive or aggressive manner. Per Bumper v. North Carolina, the use of deception to obtain consent can also in some cases prevent the search from being upheld.[citation needed]
Per Kentucky v. King, when a police officer who is not armed with a search warrant knocks on a door and requests the opportunity to speak, the occupant has no obligation to open the door or to speak.[4]