10 U.S.C. § 716

(a) Notwithstanding any other provision of law, the President, within authorized strengths and with the consent of the officer involved, may transfer any commissioned officer of a uniformed service from his uniformed service to, and appoint him in, another uniformed service. The Secretary of Defense, the Secretary of Homeland Security, the Secretary of Commerce, and the Secretary of Health and Human Services shall jointly establish, by regulations approved by the President, policies and procedures for such transfers and appointments. (b) An officer transferred under this section may not be assigned precedence or relative rank higher than that which he held on the day before the transfer.