Under regulations prescribed by the Secretary of Defense, a member described in subsection (b) may be ordered to active duty by the Secretary of the military department concerned at any time.

Except as provided in subsection (d), subsection (a) applies to the following members of the armed forces:

(1) A retired member of the Regular Army, Regular Navy, Regular Air Force, or Regular Marine Corps.

(2) A member of the Retired Reserve who was retired under section 1293, 7311, 7314, 8323, 9311, or 9314 of this title.

(3) A member of the Fleet Reserve or Fleet Marine Corps Reserve.

The Secretary concerned may, to the extent consistent with other provisions of law, assign a member ordered to active duty under this section to such duties as the Secretary considers necessary in the interests of national defense.

The following officers may not be ordered to active duty under this section:

(1) An officer who retired under section 638 of this title.

An officer who—

(A) after having been notified that the officer was to be considered for early retirement under section 638 of this title by a board convened under section 611(b) of this title and before being considered by that board, requested retirement under section 7311, 8323, or 9311 of this title; and

(B) was retired pursuant to that request.

Paragraph (1) does not apply to the following officers:

(1) A member ordered to active duty under subsection (a) may not serve on active duty pursuant to orders under that subsection for more than 12 months within the 24 months following the first day of the active duty to which ordered under that subsection.

Paragraph (1) does not apply to the following officers:

(A) A chaplain who is assigned to duty as a chaplain for the period of active duty to which ordered.

(B) A health care professional (as characterized by the Secretary concerned) who is assigned to duty as a health care professional for the period of active duty to which ordered.

(C) An officer assigned to duty with the American Battle Monuments Commission for the period of active duty to which ordered.

(D) An officer who is assigned to duty as a defense attaché or service attaché for the period of active duty to which ordered.

Subsections (d) and (e) do not apply in time of war or of national emergency declared by Congress or the President.

(Added Pub. L. 104–201, div. A, title V, § 521(a), Sept. 23, 1996, 110 Stat. 2515; amended Pub. L. 105–85, div. A, title V, § 502, Nov. 18, 1997, 111 Stat. 1724; Pub. L. 107–107, div. A, title V, § 509(a), Dec. 28, 2001, 115 Stat. 1091; Pub. L. 115–232, div. A, title VIII, § 809(a), Aug. 13, 2018, 132 Stat. 1840.)