After the assassination of JFK, the 25th Amendment was enacted. That happened in 1967. Before the passage of the 25th Amendment the Vice President didn’t officially have the power to take over as President.
The 25th Amendment states that if the president dies, resigns, or is removed from office, the vice president becomes president. And if the president is unable to fulfill his duties — like when President George W. Bush was under general anesthesia for colonoscopies in 2002 and 2007 — he can temporarily transfer his powers to the vice president, and get them back when he’s done.
But Section IV of the 25th Amendment could be a way to legally remove Trump from office.
Section IV reads:
“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.”
Section IV goes on to say that if two-thirds of both houses of Congress don’t vote to uphold the decision and keep the vice president in charge within 21 days, then the powers and duties automatically transfer back to the president.
Akhil Reed Amar, a law and political science professor at Yale University, said in a podcast for the National Constitution Center on the topic that the president’s own running mate is the one who triggers a “palace coup,” in order to maintain political stability.
“The 25th Amendment doesn’t try to specify in great detail what might count as a disability, but does try to in effect identify who and how we go about the process,” Amar said. “Here’s the key point: The vice president is the pivot in the whole process. Unless the vice president puts himself — maybe one day, herself — forward, no one else can really basically, at least within the 25th Amendment framework, proclaim an unwilling president ‘disabled.'”
The idea is that the Cabinet and VP are the president’s closest advisers. So they would be the ones with the best sense of his mental faculties. They, and Congress, could also consult doctors to evaluate the president’s physical and mental health in order to determine if he or she is fit for the job.
The 25th Amendment is a separate process from impeachment, which allows Congress to remove a sitting president if a majority of the House of Representatives votes that he has committed treason, bribery, or other high crimes and misdemeanors, and a trial in the Senate convicts him.
All in all, it has been used six times since it was passed 50 years ago, a sure indication of how important a piece of legislation it was.
Never has an American President been removed from office by use of the 25th Amendment due to mental illness…but there’s always a first.