1974—Pub. L. 93–481 struck out designation “(a)” before “A search warrant”, and struck out subsec. (b) which permitted officers authorized to execute search warrants to break open and enter premises under certain circumstances and which required that such officers identify themselves and give reasons and authority for their entry after such entry.

“United States magistrate judge” substituted in text for “United States magistrate” pursuant to section 321 of Pub. L. 101–650, set out as a note under section 631 of Title 28, Judiciary and Judicial Procedure.