The White House, Executive Order 12139: Exercise of Certain Authority Respecting Electronic Surveillance, 60 Fed. Reg., No. 103, 3 C.F.R., 1979 Comp. 397-98 (May 23, 1979) (full-text), amended by Executive Order 12333 (Dec. 4, 1981), Executive Order 13383 (2005), and Executive Order 13475 (Oct. 7, 2008).