Vanity Fair recently reported that White House sources believe the president is “unraveling.” As politicos across a widening swath of the ideological spectrum grow concerned with the president’s conduct, temperament and basic competence, references to the 25th Amendment have proliferated. It even showed up in the Vanity Fair piece: Former Trump adviser Steve Bannon told Trump that the biggest threat to his presidency wasn’t impeachment but the 25th Amendment. Trump reportedly replied, “What’s that?”

It’s a good question.

The 25th Amendment addresses two essential components of executive-branch function: presidential succession and presidential disability. Before the 25th Amendment was ratified by the requisite three-fourths of the states in 1967—after passing both houses of Congress in 1965—the practice of the vice president becoming president rather than taking over as acting president in the event that a president died was a norm, not a law. By the 1960s, there was no controversy over that convention, but Congress and the states nevertheless sought to ratify the norm as a provision of the Constitution. Section 1 of the amendment clearly states that if a president dies, resigns or is removed by Congress, “the Vice President shall become President.” Section 2 also creates a mechanism for filling the vice presidential vacancies that ensue. The third section provides a process through which presidents can voluntarily and temporarily transfer executive powers to the vice president. (Those looking for an instructive—if dramatized—primer on that matter should watch the fourth-season finale of “The West Wing,” aptly called “Twenty Five.”)

What makes the 25th Amendment of interest to Bannon—and a matter about which Trump should educate himself—is the amendment’s remedy for presidential disability, especially Section 4, which creates a mechanism for forcibly removing a president who is “unable to discharge the powers and duties of his office” but won’t admit it.

For anyone hoping for a panacean comment in the congressional record that would justify Trump’s removal, the actual history will disappoint. The history of this provision does not give much by way of directive as to when a president is disabled enough to warrant the process it creates, much less the extent to which mental eccentricities rise to the level of a disability finding. Even less does it answer the question of whether such eccentricities are valid as disabilities when they were, as in Trump’s case, plainly evident at the time of election. But the history gives a great deal of insight into the scenarios of presidential deterioration that Congress feared and how those concerns led to the procedural instrument that Congress and the states ratified.

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Most histories of the 25th Amendment begin in the moments after President John F. Kennedy’s assassination in 1963, but concerns about presidential incapacity were evident more than a century before the shooting in Dallas.

President William Henry Harrison’s most notable legacy is his unfortunate death 41 days after taking the oath of office. His death precipitated the first crisis of presidential succession and disability. The constitutional provision then in effect left doubt about how and in what capacity the vice president took over for a dead president. Article 2, Section 1, Clause 6 (which the 25th Amendment later modified) said:

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.

That language does not make clear whether a president’s death caused the vice president to assume the presidency or merely take on the presidential powers in an acting capacity until a special election chose a successor. When Harrison died, Vice President John Tyler adopted the former interpretation and took the oath of office; to quell allegations that he’d usurped the presidency, Congress voted to back him shortly thereafter. The legislature agreed that the powers of the presidency are inextricable from the office of the president; under the Constitution, there could not be an acting president.

That understanding of succession worked when a president died, and it would have worked if a president was removed or resigned. But it was troublesome in the fourth scenario that Article II covered: disability. A 1964 House report captured the problem well: “The Tyler precedent … has served to cast doubt on the ability of an incapacitated president to resume the functions of his office” (Page 4). Tyler and the legislature did not have to consider the possibility that Harrison could be able to retake office. But that scenario arose less than half a century later.

President James Garfield spent 80 days severely ill from infection after being shot in July 1882. The president’s disability was reported in major newspapers. During that time, executive-branch functions ground to a halt. Herbert Brownell Jr.—attorney general to President Dwight D. Eisenhower and an important figure in the drafting of the 25th Amendment—would later testify to Congress that “the department heads transacted only such routine business as could be transacted without the President’s supervision, and it was claimed that important questions of public policy which could be decided only by the President were simply ignored” (Page 11). The vice president, Chester A. Arthur, refused to assume the powers of the presidency on his own during Garfield’s sickness—-even though prominent academics argued at the time that the vice president had the sole discretion to declare a presidential disability. A congressional report later said that about 60 days into Garfield’s illness, his seven-member Cabinet thought it would be more prudent if Arthur acted as president. But four members firmly agreed that there was no way for Garfield to resume his office if Arthur took over. They agreed not to broach the subject further with Garfield or Arthur. The consequence for government was not lost on the media: The New York Times wrote on Aug. 15, 1881, that the paper thought the country urgently needed a mechanism for ensuring someone could exercise the presidential powers and believed “the lack of Congressional action in the past [was] a matter to be greatly deplored.” The president’s health declined for another month before he died on Sept. 19.

Nearly 40 years later, when President Woodrow Wilson fell ill in 1919, the ambiguity was an issue once again. Despite the president’s clear inability to act—some bills became law during that period because the president failed to act on them within the 10 days provided by the Constitution—the vice president refused to take on the powers and responsibilities of the presidency. One account describes:

Vice President Thomas Marshall refused to assume the presidency unless the Congress passed a resolution that the office was, in fact, vacant, and only after Mrs. Wilson and Dr. Grayson certified in writing, using the language spelled out by the Constitution, of the president’s “inability to discharge the powers and duties of the said office.” Such resolutions never came.

Marshall, like Arthur, feared that the Constitution contained no mechanism through which the president could regain his office should he recover from his illness. Only the closest advisers even knew of Wilson’s sickness; Edith Wilson kept her husband sequestered in his bedroom for most of the time between his stroke and the end of his term, and many historians have concluded that she was probably the principal decision maker for the country during that period.

Legislative Proposals

Despite the experiences of both Garfield and Wilson, Congress remained largely dormant on the issue for 30 more years. When the public learned about Wilson’s condition after his death, the House Judiciary Committee debated the question of disability but stalled over whether the remedy should be a constitutional or statutory change. Other presidents suffered from significant illnesses, both public and private, during the interregnum—Franklin Roosevelt’s polio was well known, but his doctors reportedly concealed his high blood pressure and congestive heart failure during the 1940s. Not until the Eisenhower administration did Congress take the first serious steps in the 11-year process that would ultimately produce the solution of which Bannon recently warned President Trump.

In 1955, after Eisenhower’s poor health required extended hospitalization, the president called on Congress to clarify the mechanisms for handling succession and disability. As the National Constitution Center notes, the Cold War made the possibility of a president who could not discharge the executive powers an even more frightening prospect and may have spurned Congress to act. In January 1956, the House Judiciary Committee convened a special subcommittee to study presidential disability. Despite a comprehensive digest of written and oral testimony from prominent law professors and government officials on an array of questions related to disability, the subcommittee’s work stalled shortly after considering a draft amendment in 1958.

Foremost on the subcommittee’s agenda was determining whether there was any basis to deduce what the founders meant by “inability” in the original language of the Constitution. The answer would frame whether the problem required a statutory or constitutional solution. The panel received a range of views. Several respondents said that the term could encompass any definition that Congress saw fit (with one respondent specifically mentioning that he believed mental disability should be a consideration). Others said it was deliberately vague so as not to foreclose potentially threatening scenarios that the founders didn’t or couldn’t envision. Still others said there was just no way to know. The consensus was that the term was purposely ambiguous and open to interpretation. Yet in the face of that conclusion, almost every respondent agreed that Congress should not enact a specific definition into the law. To do so would risk over-politicizing questions of a scientific and medical nature.

Moreover, experts disagreed about who should determine presidential incapacity. The questionnaire that the subcommittee distributed asked whether the vice president, the Cabinet, the Supreme Court or Congress should be responsible for the determination. Respondents suggested an inconclusive variety of permutations of one or more of those entities.

The subcommittee held hearings on at least one draft constitutional amendment. That proposal, written in close consultation with the Eisenhower administration, included provisions to address disability:

SEC. 2. If the President shall declare in writing that he is unable to discharge the powers and duties of his office, such powers and duties shall be discharged by the Vice President as Acting President. SEC. 3. If the President does not so declare, the Vice President, if satisfied of the President’s inability, and upon approval in writing of a majority of the heads of executive departments who are members of the President’s Cabinet, shall discharge the powers and duties of the office as Acting President. SEC. 4. Whenever the president declares in writing that his inability is terminated, the President shall forthwith discharge the powers and duties of his office.

During testimony before the subcommittee, Attorney General Herbert Brownell Jr. faced pushback over several points in the proposal. Some members took issue with the administration’s choice to designate the Cabinet as the determining body. Rep. Ken Keating noted that specifying that only department heads “who are members of the President’s Cabinet” could judge presidential disability left the president influence over who would participate. Brownell conceded that point, arguing that “the president should have a certain flexibility there” (Page 9). (Though that concern was ironed out in the ratified amendment, a 1981 Office of Legal Counsel memo suggests that a related controversy—whether acting heads of departments should participate in the disability determination—persisted for decades.)

At Brownell’s testimony, Rep. Emanuel Celler, the chairman of the subcommittee, said history showed that the vice president and Cabinet would be reluctant to use the power granted under Brownell’s amendment even if they had it. During Wilson’s illness, he noted, Vice President Marshall would have enjoyed support from legal scholars if he claimed he retained the authority to assume the powers of the president when Wilson became unable to fulfill his duties. But Marshall resisted. “They were not usurpers,” Celler said, “They were fearful that they might be called usurpers.” Moreover, the chairman was skeptical that passing an amendment would change the strategic calculus of the Cabinet, whose loyalty he thought would continue to lie with the president.

The attorney general rejoined that Marshall’s hesitance to take over from Wilson stemmed from the vice president’s uncertainty about whether Wilson’s disability would end and if he would be able to resume his duties. But an amendment would guarantee that if the president recovered his or her ability to perform the duties of the office, there was a clear process for returning the presidential powers. Moreover, the attorney general countered, being loyal to the president meant that invocations of the amendment would carry more legitimacy; the public could trust that those who had the president’s interest at heart were making the call. Lastly, Cabinet officers swear an oath to the Constitution, not to the president; when those duties came into tension, loyalty to the constitution should win out, Brownell argued.

Notably absent from the Eisenhower-era proposal is the provision in the modern amendment that current debate is so focused on: the power of the vice president and a majority of the Cabinet to challenge—and Congress’s subsequent power to judge—the president’s assertion that he has regained the fitness the Cabinet said he lacked.

The final version of the 25th Amendment provides that when the vice president and a majority of the Cabinet determine that the president is unable to perform his duties, the vice president becomes the acting president. Upon a written declaration by the president that the disability no longer exists, he or she resumes the office unless, within four days, the vice president and principal officers or other congressionall designated body tell Congress that they believe the president is wrong and that the disability persists. Then, Congress has 21 days to vote on the matter; with support from two-thirds majorities in the House and Senate, the vice president is to continue as acting president. If the vice president and the Cabinet do not contest the president's assertion or Congress does not vote to retain the vice president as acting president, then the president resumes office.

But there was no such mechanism in the draft before the committee. It’s perhaps not a surprise that a draft heavily influenced by the executive branch might presume that there would be no reason to challenge the president’s determination on that point, but Congressman Keating objected to this model: What would happen if the president prematurely reasserts his ability? Keating saw only two options. Either the president would fire his Cabinet, or the Cabinet would reassert the president’s incapacity. Both possibilities would halt the executive branch’s function. But the attorney general believed that impeachment was a sufficient bulwark against such a scenario.

Members of the panel seemed open to Brownell’s assessment. Some, including Keating, believed that any solution was better than the ambiguity of the constitutional provision in place at the time. But Congress ended up stalling yet again. The legislative record gives little insight into when and why the Brownell proposal failed. But for about five years, Congress ceased further consideration of the disability question.

According to a congressional report, Eisenhower reached an informal agreement with Vice President Richard Nixon that the latter would assume the powers of the office if and when he was unable. If the president could inform Nixon of the need to transfer the powers of the office, he would do so; but if the disability prevented the president from such communication, Nixon could decide to take over the office on his own until the president was able again. President Kennedy entered into a similar arrangement with Vice President Lyndon Johnson. That one was nearly put to the test.

Kennedy’s assassination in 1963 caused members of Congress to fear the narrowly averted constitutional crisis that would have ensued had Kennedy survived the shooting but in a prolonged coma. Within the year, the House and Senate judiciary committees took up, once more, the task of resolving the problem.

The committees quickly settled on the need for a constitutional amendment rather than a statutory remedy. Although Article II made clear that Congress would designate succession beyond the vice president, identical text in Senate and House judiciary committee reports showed that the committees believed the Constitution’s explicit grant of congressional power to create the line of succession meant that the founders did not intend to let Congress legislate on the question of presidential disability—a closely related topic. The committees also lacked confidence in what it viewed as the only alternative mechanism: the Article I “necessary and proper” clause.

The Constitution does not vest any department or office with the power to determine inability, or to determine the term during which the Vice President shall act, or to determine whether and at what time the President may later regain his prerogatives upon recovery. Thus, it is difficult to argue that [the necessary and proper clause] gives the Congress the authority to make all laws which shall be necessary and proper for carrying out such powers. (Page 7)

The House was prepared to enact a five-part solution that two-thirds of the Senate had already approved, the Bayh-Celler proposal (named for the chairmen of the House and Senate judiciary subcommittees on constitutional amendments). Congress had already dismissed competing proposals that addressed succession but not disability. The first two sections of the Bayh-Celler bill codified existing practices. First, the vice president would take over the office of president, not merely act as president, in the event of a president’s death, resignation or removal. Rep. Edward Hutchinson reported that “there [was] no disagreement over section 1” (Page 17). Second, if there was no vice president at any time, the president would nominate a candidate to be confirmed by a majority of the House and Senate.

The last three provisions addressed disability. Section 3 codified the practice of informal agreements that Eisenhower and Kennedy had adopted: The president could preemptively transfer his or her powers to the vice president before a period of disability. The section would create the position of acting president to distinguish this case from the dilemmas that Vice Presidents Tyler, Arthur and Marshall had faced.

Sections 4 and 5 created the provision of greatest importance to the late unpleasantness. Section 4 provided that with the support of a majority of the “principal officers of the executive departments,” the vice president could assume the powers of the presidency. Congress derived the “principal officers” language from the opinions clause of Article II. (“[H]e may require the Opinion in writing, of the principal Officer in each of the executive Departments.”) By dropping Brownell’s proposed requirement that an officer be a “member of the President’s cabinet,” the president could not exclude a principal officer from the deliberation by removing him or her from the Cabinet.

A House report notes the past controversy over the determining body and engages particularly with the proposal of a fact-finding commission. Rather shortsightedly, the report suggests that “If the President is so incapacitated that he cannot declare his own inability the factual determination of inability would be relatively simple” and that there would be no need for a fact-finding body. (It seems like nearly nothing is simple about determining whether a president is disabled despite his or her belief to the contrary.) The report further said that in hard cases, the risk that a commission would return a split decision was unacceptably high. If a commission returned a 4-3 vote either to remove to retain the president, it would shatter the legitimacy of whoever held presidential powers afterward: “[T]he effect on the international position of the United States might well be catastrophic.” Nevertheless, the amendment would give Congress authority to empower another body, providing “flexibility for the future.”

Section 5 (which was reorganized under Section 4 in conference committee) provides that the president may resume the office by submitting a written declaration to the speaker of the House and the president of the Senate that no disability exists. If the vice president and a majority of the Cabinet disagree with the president’s judgment, then they must give a written declaration to the House speaker and president of the Senate within two days. Congress must then decide within 10 days whether the disability persists; a two-thirds vote of both houses can override the president’s determination. (Peculiarly, the report cites the impeachment provision of Article 1, Section 3, Clause 6 as the basis for the two-thirds threshold, even though impeachment requires only a majority of the House and two-thirds of the Senate.) Otherwise, the president resumes office.

But the views that the House and Senate committees put forward were not without dissent; rather, both included memos from individual members who disagreed with the structure of the amendment. Perhaps most notable were two warnings from Rep. J. Edward Hutchinson. Regarding Section 4, he noted: “The language of the resolution offers no hint that the determination of inability shall be based on medical or psychiatric evidence. Instead, the determination will be a political one” (Page 19).

Perhaps more gravely, Hutchinson feared that the mechanism of Section 4 risked significantly destabilizing the executive branch. A president’s credibility would be pitiful if his or her assertion of ability was sustained by more than a third but less than a majority of Congress. Moreover, as Attorney General Brownell had noted almost a decade earlier, the Cabinet and vice president might try to remove the president once again. The president could remove executive officers, but doing so would leave Cabinet offices unfilled and disrupt the function of those departments.

With changes to how long the Cabinet (four days) and Congress (21 days, and meeting within 48 hours if not in session) have to act after the president tells Congress he has no disability, and over the objections of Hutchinson and a few others, the bill cleared both the House and Senate with the requisite supermajorities on July 6, 1965. It was ratified by its 38th state on Feb. 10, 1967.

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In September, Jane Chong observed two myths about impeachment: that the process is purely political, and that the House cannot begin considering it without clear evidence of criminality. One can say something similar about the 25th Amendment. The process is not purely political, though the final mechanism is a political process. And there’s no particular threshold that needs to be reached before the relevant body—in this case the Cabinet—starts thinking about it. That said, objective criteria like medical considerations should be at the fore. (A 1983 Miller Center commission co-chaired by Sen. Birch Bayh and Attorney General Brownell endorses the view that science should be central to the judgment.) And a Cabinet should always be vigilant about signs of presidential disability; it is the constitutional duty of Cabinet officers.

Each citizen should draw his or her own conclusion about presidential disability. But make no mistake: Invoking Section 4 would have a dramatic and potentially dangerous effect on our politics. Even if meticulously executed, the process is fraught with political pitfalls that could further undermine divisions among the public and legitimacy in U.S. institutions.

So although Bannon might have been right that the 25th Amendment could pose a real threat to the Trump presidency, it should give the president's political opponents little, if any, solace.

Correction: This post was updated on Oct. 24 at 10:49 a.m. A previous version incorrectly stated that the 25th Amendment allows the vice president and principal officers of the executive departments two days, and Congress, 10 days, to act if the president asserts that he has no disability. The amendment gives four and 21 days, respectively.