§ 138. Assistant Secretaries of Defense

(a)
(1) There are 16 Assistant Secretaries of Defense.
(2) The Assistant Secretaries of Defense shall be appointed from civilian life by the President, by and with the advice and consent of the Senate.
(b)
(1) The Assistant Secretaries shall perform such duties and exercise such powers as the Secretary of Defense may prescribe.
(2) One of the Assistant Secretaries is the Assistant Secretary of Defense for Reserve Affairs. He shall have as his principal duty the overall supervision of reserve component affairs of the Department of Defense.
(3) One of the Assistant Secretaries is the Assistant Secretary of Defense for Homeland Defense. He shall have as his principal duty the overall supervision of the homeland defense activities of the Department of Defense.
(4) One of the Assistant Secretaries is the Assistant Secretary of Defense for Special Operations and Low Intensity Conflict. He shall have as his principal duty the overall supervision (including oversight of policy and resources) of special operations activities (as defined in section 167 (j) of this title) and low intensity conflict activities of the Department of Defense. The Assistant Secretary is the principal civilian adviser to the Secretary of Defense on special operations and low intensity conflict matters and (after the Secretary and Deputy Secretary) is the principal special operations and low intensity conflict official within the senior management of the Department of Defense.
(5) One of the Assistant Secretaries is the Assistant Secretary of Defense for Legislative Affairs. He shall have as his principal duty the overall supervision of legislative affairs of the Department of Defense.
(6) One of the Assistant Secretaries is the Assistant Secretary of Defense for Acquisition. The Assistant Secretary of Defense for Acquisition is the principal adviser to the Secretary of Defense and the Under Secretary of Defense for Acquisition, Technology, and Logistics on matters relating to acquisition.
(7) One of the Assistant Secretaries is the Assistant Secretary of Defense for Logistics and Materiel Readiness. In addition to any duties and powers prescribed under paragraph (1), the Assistant Secretary of Defense for Logistics and Materiel Readiness shall have the duties specified in section 138a of this title.
(8) One of the Assistant Secretaries is the Assistant Secretary of Defense for Research and Engineering. In addition to any duties and powers prescribed under paragraph (1), the Assistant Secretary of Defense for Research and Engineering shall have the duties specified in section 138b of this title.
(9) One of the Assistant Secretaries is the Assistant Secretary of Defense for Operational Energy Plans and Programs. In addition to any duties and powers prescribed under paragraph (1), the Assistant Secretary of Defense for Operational Energy Plans and Programs shall have the duties specified in section 138c of this title.
(10) One of the Assistant Secretaries is the Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs. In addition to any duties and powers prescribed under paragraph (1), the Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs shall have the duties specified in section 138d of this title.
(c) Except as otherwise specifically provided by law, an Assistant Secretary may not issue an order to a military department unless—
(1) the Secretary of Defense has specifically delegated that authority to the Assistant Secretary in writing; and
(2) the order is issued through the Secretary of the military department concerned.
(d) The Assistant Secretaries take precedence in the Department of Defense after the Secretary of Defense, the Deputy Secretary of Defense, the Secretaries of the military departments, the Under Secretaries of Defense, the Deputy Chief Management Officer of the Department of Defense, the officials serving in positions specified in section 131 (b)(4) of this title, and the Principal Deputy Under Secretaries of Defense. The Assistant Secretaries take precedence among themselves in the order prescribed by the Secretary of Defense.