10 USC 10505 - Director of the Joint Staff of the National Guard Bureau

(a) Appointment.— 

(1) There is a Director of the Joint Staff of the National Guard Bureau, selected by the Secretary of Defense from officers of the Army National Guard of the United States or the Air National Guard of the United States who
(A) are recommended for such appointment by their respective Governors or, in the case of the District of Columbia, the commanding general of the District of Columbia National Guard;
(B) have had at least 10 years of federally recognized commissioned service in an active status in the National Guard; and
(C) are in a grade above the grade of colonel.
(2) The Chief of the National Guard Bureau and the Director of the Joint Staff of the National Guard Bureau may not both be members of the Army or of the Air Force.
(3) 
(A) Except as provided in subparagraph (B), an officer appointed as Director of the Joint Staff of the National Guard Bureau serves for a term of four years, but may be removed from office at any time for cause.
(B) The term of the Director of the Joint Staff of the National Guard Bureau shall end upon the appointment of a Chief of the National Guard Bureau who is a member of the same armed force as the Director.
(4) The Secretary of Defense may waive the restrictions in paragraph (2) and the provisions of paragraph (3)(B) for a limited period of time to provide for the orderly transition of officers appointed to serve in the positions of Chief of the National Guard Bureau and the Director of the Joint Staff of the National Guard Bureau.
(b) Duties.— 
The Director of the Joint Staff of the National Guard Bureau performs such duties as may be prescribed by the Chief of the National Guard Bureau.
(c) Grade.— 
The Director of the Joint Staff of the National Guard Bureau shall be appointed to serve in the grade of major general.