In addition, border searches may take place at the functional equivalent of the border if the search takes place at the first practicable point after the border was crossed and the object of the search had no opportunity to change materially since the time of the crossing. Moreover, according to the decision in United States v. Brennan, the mobility of an aircraft justifies government agents' permitting a smuggling suspect to reach a secure location before conducting the border search. Finally, Maryland v. Buie holds that police officers can do a protective "sweep" search of suspect premises to reduce the possible danger to themselves or others.