10 U.S.C. § 8044 — Assistant Commandant of the Marine Corps

(a) There's an Assistant Commandant of the Marine Corps, appointed by the President with Senate approval, chosen from active-duty Marine Corps officers who aren't restricted from duty. (b) While serving, the Assistant Commandant holds the grade of general without losing their permanent grade. (c) The Assistant Commandant has whatever authority and duties the Commandant delegates or sets, with the Secretary of the Navy's approval. Orders the Assistant Commandant gives while performing these duties count the same as orders from the Commandant. (d) If the office of Commandant is vacant, or the Commandant is absent or unable to serve: (1) the Assistant Commandant performs the Commandant's duties until a successor is appointed or the absence or disability ends; or (2) if the Assistant Commandant's office is also vacant, or the Assistant Commandant is absent or unable to serve, then — unless the President says otherwise — the most senior available Marine Corps officer in Headquarters, Marine Corps, who isn't restricted from duty performs the Commandant's duties, until a successor is appointed or the absence or disability of either officer ends, whichever happens first.