Basically, at the moment, nothing — even though the guy has his finger on the nuclear button.
The New Yorker has a piece by Jeannie Suk Gersen, a Harvard law professor, asking the question “Will Trump be the death of the Goldwater rule?”
“The class of professionals best equipped to answer these questions”, she writes,
has largely abstained from speaking publicly about the President’s mental health. The principle known as the “Goldwater rule” prohibits psychiatrists from giving professional opinions about public figures without personally conducting an examination, as Jane Mayer wrote in this magazine in May. After losing the 1964 Presidential election, Senator Barry Goldwater successfully sued Fact magazine for defamation after it published a special issue in which psychiatrists declared him “severely paranoid” and “unfit” for the Presidency. For a public figure to prevail in a defamation suit, he must demonstrate that the defendant acted with “actual malice”; a key piece of evidence in the Goldwater case was Fact’s disregard of a letter from the American Psychiatric Association warning that any survey of psychiatrists who hadn’t clinically examined Goldwater was invalid.
There’s something comical about this, in the sense that if any of these august professionals did indeed conduct an examination of the president, then they would be bound by patient confidentiality and so would be unable to contribute to a public discussion on his mental state.
Not being a psychiatrist, I am unfettered by these considerations and indeed performed my own examination of the question some time ago. I dug out the Mayo Clinic’s list of the symptoms and causes of ‘Antisocial Personality Disorder’ (aka sociopathy) and concluded that Trump ticked most of the boxes. I also quoted the only commentator I could find who openly approached the question of whether Trump is unhinged — Andrew Sullivan — and who had also concluded in the affirmative.