The chairman of the Joint Chiefs of Staff (CJCS) is the presiding officer of the Joint Chiefs of Staff (JCS). The chairman is the highest-ranking and most senior military officer in the United States Armed Forces and 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, the chairman is prohibited by law from having operational command authority over the armed forces; however, the chairman assists 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, 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 commandant of the Marine Corps, the chief of naval operations, the chief of staff of the Air Force, the chief of space operations, 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 the secretary of defense.