“The Department of Justice believes, and the case law supports, that the president has inherent authority to conduct warrantless physical searches for foreign intelligence purposes, and that the president may, as has been done, delegate this authority to the attorney general. It's important to understand, senators, that the rules and the methodology for criminal searches are inconsistent with the collection of foreign intelligence and would unduly frustrate the president in carrying out his foreign intelligence responsibilities.”
Source : Jamie Gorelick's statement on wireless physical searches before the US House of Representatives permanent Select Committee on intelligence, thinkprogress.org. December 20, 2005. 
