The Goldwater-Nichols DOD Reorganization Act of 1986 identifies the Chairman of the Joint Chiefs of Staff as the senior ranking member of the Armed Forces. As such, the Chairman of the Joint Chiefs of Staff is the principal military adviser to the President. He may seek the advice of and consult with the other JCS members and combatant commanders. When he presents his advice, he presents the range of advice and opinions he has received, along with any individual comments of the other JCS members.
Under the DOD Reorganization Act, the Secretaries of the Military Departments assign all forces to combatant commands except those assigned to carry out the mission of the Services, i.e., recruit, organize, supply, equip, train, service, mobilize, demobilize, administer and maintain their respective forces. The chain of command to these combatant commands runs from the President to the Secretary of Defense directly to the commander of the combatant command. The Chairman of the Joint Chiefs of Staff may transmit communications to the commanders of the combatant commands from the President and Secretary of Defense but does not exercise military command over any combatant forces.
The Act also gives to the Chairman of the Joint Chiefs of Staff some of the functions and responsibilities previously assigned to the corporate body of the Joint Chiefs of Staff. The broad functions of the Chairman of the Joint Chiefs of Staff are set forth in Title 10, United States Code, and detailed in DOD Directive 5100.1. In carrying out his duties, the Chairman of the Joint Chiefs of Staff consults with and seeks the advice of the other members of the Joint Chiefs of Staff and the combatant commanders, as he considers appropriate.