In the aftermath of the assassination of President John F. Kennedy in 1963, the nation soon asked questions about the presidency. Questions arose about what would have happened if Kennedy had somehow survived but with a severe brain injury or surviving only on life support systems beginning to become available at the time. Vice-President Lyndon Johnson had now become president, and he discussed these concerns with aides and members of Congress. The result was a new amendment to the Constitution.


Including the murder of Kennedy, eight presidents had died in office. Seven vice-presidents had died in office, and one had resigned up to 1964. In spite of these circumstances, the Constitution never made clear what would happen if the presidency became vacant, simply stating that the vice-president would assume the duties of the president, not necessarily becoming president. And the vice-presidency itself would remain vacant until a new one was elected.


Other scenarios prompted questions as to what would happen if a president were somehow physically incapacitated or mentally or psychologically unable to serve. When President Woodrow Wilson had a massive stroke in 1919, he was initially left mostly paralyzed and almost completely uncommunicative for days before he began to recover. Even the most modest medical techniques to treat stroke patients were still decades away. Vice-President Thomas Marshall refused to assume the duties of the presidency while Wilson convalesced, fearing the dangerous precedent it could set as the Constitution provided no guidance for such a situation. Wilson never fully recovered.


Sometimes the vice-presidents themselves posed special problems. Vice-President Aaron Burr killed former Treasury Secretary Alexander Hamilton in an 1804 duel and faced murder charges in New York and New Jersey. Vice-Presidents Daniel Tompkins and Andrew Johnson were both alcoholics. Johnson appeared at his own inauguration as vice-president in 1865 completely drunk.


President Dwight Eisenhower suffered a major heart attack in 1956 that left him incapacitated for several weeks. The tensions of the Cold War only emphasized the need for president being able to make difficult decisions without delay.


When Johnson delivered his State of the Union Address in January 1964, the image was striking: the next two men in line to the presidency were Senate President pro tem Carl Hayden, the 86-year-old veteran Arizona Senator, and House Speaker John McCormack of Massachusetts, age 72. There was no vice-president sitting behind him as the position had been vacant since Johnson, who himself had a heart attack years before, became president two months earlier.


Sen. Birch Bayh of Indiana and Rep. Emmanuel Celler of New York introduced an amendment in 1965. Arkansas’s own Sen. John McClellan sat on the Senate Judiciary Committee at the time and helped craft the amendment and guide it through hearings. What became the 25th Amendment enshrined into the Constitution that the vice-president would become the president in power and name if the presidency was vacated. The vice-presidency would be filled by a nomination made by the president and approved by a majority vote of both houses of Congress. The president can voluntarily sign over his duties temporarily to the vice-president as acting president in a letter to Congress.


However, the vice-president and a majority of the presidential cabinet (now numbering 15) inform Congress that the president cannot perform his duties, and the vice-president immediately becomes acting president. However, if a dispute ever arose between the president and his cabinet over his disability, the president can report to Congress that no disability exists and remain president. If the cabinet persists, then Congress settles the matter and must vote within 21 days whether the president is fit. Otherwise, the president automatically resumes his duties.


The House passed the final version by a voice vote on June 30. On July 6, the Senate voted to approve it. McClellan voted to approve, but his Arkansas counterpart, Sen. J. William Fulbright, was not present for the vote.


Arkansas became the eleventh state to ratify the amendment, approving it on November 4, 1964. Nevada became the 38th state to ratify the amendment on February 10, 1967, meeting the required number of states for ratification. Forty-seven states would ratify it.


Within the next few decades, the amendment would be invoked on several occasions. Vice-President Spiro Agnew resigned in 1973 following a conviction on income tax evasion charges. President Richard Nixon selected Congressman Gerald Ford to be the new vice-president. Nixon was forced to resign in 1974 in the wake of the Watergate scandal, making Ford the new president. Ford then chose former New York Governor Nelson Rockefeller as his vice-president, which was quickly approved by Congress. When President Ronald Reagan underwent surgery in 1985, Vice-President George Bush became acting president while Reagan was under anesthesia.


Questions, however, still persist about how the amendment should be utilized, especially if presidents should fall prey to illness that very gradually robbed them of their reasoning abilities or a mental illness.