《美利坚合众国宪法》第二十五修正案（英語：Twenty-fifth Amendment to the United States Constitution）簡稱「第二十五修正案」（Amendment XXV），对美国总统和副总统职位因各种原因出现空缺时的继任程序作出了修正和规定，并增加了由副总统和内阁成员判断总统是否能够继续履行职责的新条款。宪法第二条第一款第六节中所规定的继任程序遣词并不明确，其中没有说明“如遇总统被免职、死亡、辞职或丧失履行总统权力和责任的能力时”[1][2]，副总统究竟应该成为新任总统还是代理总统[3]，亦未规定若副总统“被免职、死亡、辞职或丧失履行时”，副总统权力和责任的能力时又该如何處理，第二十五修正案对这两方面问题都作出了明确的回答。修正案于1965年7月6日由联邦国会提出，1967年2月10日获得了足够数量州的批准而生效[4]。
1965年1月6日，宪法修正案小组委员会新任主席（接替基福弗），来自印第安纳州的联邦参议员比奇·贝耶（英语：Birch Bayh）在参议院提交了新的修正案提案，众议院司法委员会（英语：United States House Committee on the Judiciary）主席，来自纽约州的众议员伊曼纽尔·塞勒（英语：Emanuel Celler）也在众议院提交了同一个提案，该提案就是之后第二十五修正案的原型。其中明确规定了宣布总统不能够履行其权责的具体程序，并且这一类情况下副总统将成为代理总统，总统之后也可以通过明确的程序来恢复自己的权责。提案中还规定了副总统出现空缺时的填补程序。贝耶—塞勒提案与基廷—基福弗提案恰好相反，后者没有提供副总统职位空缺的填补程序，也没有对宣布总统无法履职的程序作出规定。1964年，美国律师协会表示支持贝耶—塞勒提案[10]:348-350。
下午，里根与白宫律师弗里德·F·菲尔汀（Fred F. Fielding）通了电话，讨论是否应该使用第二十五修正案，如果使用，这一权力的移交又是否会成为一个不良先例。菲尔汀与白宫办公厅主任唐纳德·里甘为此建议总统写下两封信来移交权力，第一封明确援引第二十五修正案第三款，第二封则不援引修正案。次日上午10:32，里根在第二封信上签字并指示将信送交修正案所规定的官员[19]。
原文为：Section 2. Whenever there is a vacancy in the office of the Vice President, the President shall nominate a Vice President who shall take office upon confirmation by a majority vote of both Houses of Congress.
原文为：Section 3. Whenever the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that he is unable to discharge the powers and duties of his office, and until he transmits to them a written declaration to the contrary, such powers and duties shall be discharged by the Vice President as Acting President.
原文为：Section 4. Whenever the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide, transmit to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President.
Thereafter, when the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that no inability exists, he shall resume the powers and duties of his office unless the Vice President and a majority of either the principal officers of the executive department or of such other body as Congress may by law provide, transmit within four days to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office. Thereupon Congress shall decide the issue, assembling within forty-eight hours for that purpose if not in session. If the Congress, within twenty-one days after receipt of the latter written declaration, or, if Congress is not in session, within twenty-one days after Congress is required to assemble, determines by two-thirds vote of both Houses that the President is unable to discharge the powers and duties of his office, the Vice President shall continue to discharge the same as Acting President; otherwise, the President shall resume the powers and duties of his office.
In Case of the Removal of the President from Office, or of his Death, Resignation, or Inability to discharge the Powers and Duties of the said Office, the Same shall devolve on the Vice President, and the Congress may by Law provide for the Case of Removal, Death, Resignation or Inability, both of the President and Vice President, declaring what Officer shall then act as President, and such Officer shall act accordingly, until the Disability be removed, or a President shall be elected.
原文为：In case of the removal of the President from office or of his death or resignation, the said office shall devolve on the Vice President. In case of the inability of the President to discharge the powers and duties of the said office, the said powers and duties shall devolve on the Vice President, until the inability be removed. The Congress may by law provide for the case of removal, death, resignation or inability, both of the President and Vice President, declaring what officer shall then be President, or, in case of inability, act as President, and such officer shall be or act as President accordingly, until a President shall be elected or, in case of inability, until the inability shall be earlier removed. The commencement and termination of any inability shall be determined by such method as Congress shall by law provide.
This was a cataclysmic "cerebrovascular accident" (stroke) that left him with a dense and permanent paralysis of the left side of his body (hemiplegia), as well as hemianopsia. Park BE, The Impact of Illness of World Leaders (University of Pennsylvania Press, Philadelphia, 1986), pp. 3-76
