Section 4 (the only section of the amendment that has never been invoked) addresses the case of an incapacitated president who is unable or unwilling to execute the voluntary declaration contemplated in Section 3. It allows the vice president, together with a "majority of either the principal officers of the executive departments or of such other body as Congress may by law provide", to issue a written declaration that the president is "unable to discharge the powers and duties" of their office. Upon such a declaration being made, the vice president immediately becomes acting president while (as with Section 3) the president remains in office, albeit divested of all authority.[6]