On September 25, 2001, “John Yoo, a Justice Department lawyer in the Office of Legal Counsel, wrote an internal memorandum that argued that the government might use ‘electronic surveillance techniques and equipment that are more powerful and sophisticated than those available to law enforcement agencies in order to intercept telephonic communications and observe the movement of persons but without obtaining warrants for such uses.’ Yoo noted that while such actions could raise constitutional issues, in the face of devastating terrorist attacks, he wrote, ‘the government may be justified in taking measures which in less troubled conditions could be seen as infringements of individual liberties.’ “
– James Risen, State of War, Pages 57-58