The Chairman of the Joint Chiefs of Staff (CJCS) is, by U.S. law, the highest-ranking and senior most military officer in the United States Armed Forces and is the principal military advisor to the President, the National Security Council, the Homeland Security Council, and the Secretary of Defense. While the Chairman of the Joint Chiefs of Staff outranks all other commissioned officers, he is prohibited by law from having operational command authority over the armed forces; however, the Chairman does assist the President and the Secretary of Defense in exercising their command functions.
The Chairman convenes the meetings and coordinates the efforts of the Joint Chiefs of Staff (JCS), an advisory body within the Department of Defense comprising the Chairman, the Vice Chairman of the Joint Chiefs of Staff, the Chief of Staff of the Army, the Chief of Naval Operations, the Chief of Staff of the Air Force, the Commandant of the Marine Corps, and the Chief of the National Guard Bureau. The post of a statutory and permanent Joint Chiefs of Staff chair was created by the 1949 amendments to the National Security Act of 1947. The 1986 Goldwater-Nichols Act elevated the Chairman from the first among equals to becoming the "principal military advisor" to the President and Secretary of Defense.