It’s true that the use of Section 4’s involuntary-removal mechanism for the first time in American history—especially for a president who is not ill and who still has public support—could trigger a political crisis. Still, the constitutional test of the president’s being “unable to discharge the powers and duties” of the office was intended to be vague and open-ended. In 1995, Senator Birch Bayh, the father of the Twenty-Fifth Amendment, quoted President Dwight Eisenhower, whose illness had helped to precipitate the drafting of the amendment, in support of the proposition that “the determination of the president’s disability is really a political question.”

In other words, both the president whose disability inspired the Twenty-Fifth Amendment and the senator who helped to draft it viewed the definition of “disability” under the amendment not as a medical decision, left to doctors, but a political decision, left to the vice president, the Cabinet, and ultimately Congress. If, at some point in the future, those officers decide it is more politically advantageous for the Republican Party to remove Trump under the Twenty-Fifth Amendment than to allow him to be impeached for obstruction of justice, nothing in the text or original understanding of the amendment would prevent them from doing so.

Because predicting the political future is impossible, let’s take a deep dive into the history and original understanding of the Twenty-Fifth Amendment. That history suggests that Section 4 of the amendment was intended involuntarily to remove presidents who were clearly and unequivocally incapacitated to the point of being unable to discharge their duties—in other words, terminally ill, in a coma, near death, or severely mentally incapacitated. But the precise definition of disability was left to the political process.

As Scott Bomboy has reported in a series of posts on the National Constitution Center’s Constitution Daily, a presidential succession amendment was first contemplated after President Dwight Eisenhower’s illness in the 1950s and became a reality after the Kennedy Assassination in 1963:

By 1963, Congress was debating an attempt to amend the Constitution to clear up all succession matters and add a procedure for dealing with a leader who became unable to perform the office’s duties temporarily or permanently. This became a bigger issue with the realities of the Cold War and with President Dwight Eisenhower’s illnesses in the 1950s. The influential Senator Estes Kefauver had started the amendment effort during the Eisenhower era, and he renewed it in 1963. Kefauver died in August 1963 after suffering a heart attack on the Senate floor. With Kennedy’s unexpected death, the need for a clear way to determine presidential succession, especially with the new reality of the Cold War and its frightening technologies, forced Congress into action. The new President, Lyndon Johnson, had known health issues, and the next two people in line for the presidency were 71-year-old John McCormack (the Speaker of the House) and Senate Pro Tempore Carl Hayden, who was 86 years old.

The principal sponsor of the Twenty-Fifth Amendment was Bayh, chair of the Senate Judiciary Subcommittee on the Constitution and Civil Justice, responsible for proposing constitutional amendments. Bayh served as the subcommittee’s chair for nearly two decades and he drove the process that resulted in the Twenty-Fifth and Twenty-Sixth Amendments to the Constitution. (A third amendment championed by Bayh, the Equal Rights Amendment, was approved by the House and Senate, but it fell three states short of full ratification. But Bayh is still the only non-founding father to draft two enacted amendments to the U.S. Constitution.) Bayh proposed what became the Twenty-ifth Amendment on January 6, 1965, and it was ratified on February 10, 1967, 50 years ago.