The Patriot Act expired on Sunday night, leaving the United States government with fewer tools to investigate terrorism following the initiation of the law in the wake of the September 11 Twin Tower bombings. The Senate entered a debate on the Patriot Act on Sunday with some officials warning of continued national security risks. Telephone metadata on millions of Americans, stored for five years, will no longer be allowed. Nor will law enforcement officials be allowed to get a roving wiretrap to track terror suspects who frequently change communications devices, like phones. Now, warrants will be needed.