The FBI is responsible for both intelligence and law enforcement with more than 36,000 employees. It has faced questions in recent weeks over media leak probes involving The Associated Press and Fox News; the Boston Marathon bombings; the attack at Benghazi, Libya, that killed four Americans; and two vast government surveillance programs into phone records and online communications.
The leaker of those National Security Agency programs, former NSA contractor Edward Snowden, also is the subject of an ongoing criminal investigation. And just this week Mueller revealed the FBI uses drones for surveillance of stationary subjects and said the privacy implications of such operations are worthy of debate.
Comey played a central role in holding up Bush's warrantless wiretapping program, one of the administration's great controversies and an episode that focused attention on the administration's controversial tactics in the war on terror.
In dramatic testimony to the Senate Judiciary Committee in 2007, Comey said he thought the no-warrant wiretapping program was so questionable that he refused to reauthorize it while serving as acting attorney general during Ashcroft's hospitalization. Comey said when he learned that the White House chief of staff and counsel were heading to Ashcroft's room despite his wife's instructions that there be no visitors, Comey beat them there and watched as Ashcroft turned them away.
"That night was probably the most difficult night of my professional life," Comey testified. He said he and Ashcroft had reservations about the program's legality, but he would not discuss details since the program was classified.
Senior government officials had expressed concerns about whether the NSA, which administered the warrantless eavesdropping program, had the proper oversight in place. Other concerns included whether any president possessed the legal and constitutional authority to authorize the program as it was carried out at the time.