14 U.S.C. § 103 — Department in which the Coast Guard operates

(a) In General. The Coast Guard is normally a service inside the Department of Homeland Security, except when it operates as part of the Navy. (b) Transfers. If Congress declares war and directs it, or if the President orders it, the Coast Guard switches to operate as part of the Navy. It stays there until the President, by executive order, moves it back to the Department of Homeland Security. While serving under the Navy, the Coast Guard follows the Secretary of the Navy's orders, and that Secretary can adjust Coast Guard operations to match Navy operations, as far as the Secretary thinks is wise. (c) Operation as a Service in the Navy. Whenever the Coast Guard operates under the Navy: (1) Navy Department funds can be used to cover Coast Guard costs; (2) Coast Guard funds can be transferred to the Navy Department; (3) rank order between Coast Guard and Navy officers of matching grades is set by the date shown on their commissions; (4) Coast Guard personnel can get the same medals, honors, and gratuities as Navy personnel or people serving with the Navy; and (5) the Secretary can place any Coast Guard officer on furlough — those officers get half of their normal leave pay — but Coast Guard Reserve officers cannot be furloughed this way.