10 U.S.C. § 14906

(a) Composition of Boards .— Each board convened under this chapter shall consist of officers appointed as follows: (1) Each member of the board shall be an officer of the same armed force as the officer being required to show cause for retention in an active status. (2) Each member of the board shall hold a grade above major or lieutenant commander, except that at least one member of the board shall hold a grade above lieutenant colonel or commander. (3) Each member of the board shall be senior in grade to any officer to be considered by the board. (b) Limitation .— A person may not be a member of more than one board convened under this chapter to consider the same officer.