When a big, black SUV would pull up to my house at about 2 a.m., I knew it would be a while before I’d be getting back to sleep. As the CIA’s deputy director, and later acting director, in the early 2000s, I was frequently awakened via secure communications at home. But when a car showed up, it meant that something needed my official signature – usually a warrant request under the Foreign Intelligence Surveillance Act, or FISA. The FBI would be asking me to sign off because the request contained foreign intelligence material, often relating to a terrorism suspect. These things typically ran 40 to 60 pages. They would contain reporting from human sources (foreign agents), technical intelligence such as intercepted communications, and open-source material. These were woven together into a request aimed at showing “probable cause” to investigate further by carrying out some kind of search.