Section 4 is the only part of the amendment that has never been invoked. 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 declare the President "unable to discharge the powers and duties of his office '' by submitting a written declaration to the President pro tempore of the Senate and the Speaker of the House of Representatives. As with Section 3, the Vice President would become Acting President.
who determines if the president is unfit to serve
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 ''