In his memoir, former CIA Director George J. Tenet described the agency's first course of action in a crisis. "Despite what Hollywood might have you believe," Tenet wrote, "you don't call in the tough guys; you call in the lawyers." For more than three decades, that almost always has meant making a call to John A. Rizzo. The acting general counsel at the CIA, Rizzo has guided generations of agency leaders on the legal contours of clandestine operations and the often-ensuing investigations. At CIA headquarters, he is known for his eye-watering wardrobe -- with ties, cuff links and suspenders colored...