In the midst of a deeply divisive presidential campaign, more than 1,000 psychiatrists declared the Republican candidate unfit for the office, citing severe personality defects, including paranoia, a grandiose manner and a Godlike self-image. One doctor called him “a dangerous lunatic.”

The year was 1964, and after losing in a landslide, the candidate, Senator Barry Goldwater of Arizona, sued the publisher of Fact magazine, which had published the survey, winning $75,000 in damages.

But doctors attacked the survey, too, for its unsupported clinical language and obvious partisanship. In 1973, the American Psychiatric Association adopted what became known as the Goldwater Rule, declaring it unethical for any psychiatrist to diagnose a public figure’s condition “unless he or she has conducted an examination and has been granted proper authorization for such a statement.”

Enter Donald J. Trump.

John Oliver didn't need to diagnose Trump's condition to recommend that he drop out.

http://www.thedailybeast.com/articles/2016/08/22/john-oliver-to-trump-drop-out-and-you-would-be-a-legend.html