THE MATTIS WAIVER: The full Senate approved, the House Armed Services Committee approved. “Mattis now needs only approval from the full House of Representatives.”

Normally the SecDef must “be at least seven years removed from active military duty.” Mattis retired in 2013.

Congress created the mandate with the National Security Act of 1947 — believing civilian leadership in the Pentagon ensures the fewest question marks for military policy, which has the potential to be unpopular with active duty members of the armed forces.

Only one waiver has ever been granted by Congress, for active U.S. Army Gen. George C. Marshall in 1950.