Is President Trump mentally ill, suffering from dementia, or both? Some mental health professionals and others are arguing that he should be removed from office because the answer to at least one of those questions is “yes.” I believe this is a dangerous course to follow.

A Yale psychiatry professor has suggested the possibility that President Trump might be involuntarily committed to a mental hospital. Others have proposed that he be required to undergo psychiatric or psychological testing. Still others have suggesting invoking the 25thAmendment to the Constitution and declaring the president incompetent.

For more than 25 years, I taught courses on law and psychiatry, and related subjects, at Harvard Law School. I co-edited a basic text in the field. And I have written numerous articles regarding the ability and inability of psychiatrists to predict future conduct.

On the basis of my research and writing, I find it unprofessional, unethical, and absurd for any mental health professional who has not examined President Trump to offer a diagnosis or psychiatric prediction about him.

We are all entitled to our opinions regarding the president’s political and personal qualifications to serve. I voted for Hillary Clinton in the last election because I felt she was more qualified than Donald Trump to be president. That is my right as an American voter.

But psychiatrists and other mental health professionals have no more right to pathologize a president or a candidate because they disagree with his or her political views than do prosecutors or politicians have a right to criminalize political opponents.

I have been writing in opposition to the criminalization of political differences for decades, because it is dangerous to democracy. It is even more dangerous to pathologize or psychiatrize one’s political opponents based on opposition to their politics.

Getting mental health professionals to declare political opponents mentally ill was a common tactic used against political dissidents by the Soviet Union, China, and apartheid South Africa. Perfectly sane people were locked up in psychiatric wards or prisons for years because of phony diagnoses of mental illness.

The American Psychiatric Association took a strong stand against the use of this weapon by tyrants. I was deeply involved in that condemnation, because I understood how dangerous it is to diagnose political opponents instead of responding to the merits of their political views.

It is even more dangerous when a democracy like the U.S. begins to go down the road of pathologizing political differences. It’s one thing to say your opponents are wrong. It’s quite another to say they are crazy.

Questions about President Trump’s mental health arose even before he was elected. Throughout the 2016 presidential campaign, some of his most extreme critics were not content to say they disagreed with his policies – or thought he was unqualified because of his temperament, background, or skill set. Instead, they questioned his mental health.

I am old enough to remember the last time this happened. The 1964 presidential election was the second in which I voted. President Lyndon Johnson, who had succeeded the assassinated President John F. Kennedy, was running against Sen. Barry Goldwater, R-Ariz.

I didn’t like either candidate. Johnson’s personal characteristics were obnoxious, though he had achieved much, especially in the area of civil rights. Goldwater’s personal characteristics seemed fine, but I disapproved of his conservative political views.

I was shocked to read an article in Fact magazine – based on interviews with more than 1,100 psychiatrists – that concluded Goldwater was mentally unstable and psychologically unfit to be president. It was Lyndon Johnson whose personal fitness to hold the highest office I had questioned.

Goldwater seemed to me to be emotionally stable, with excellent personal characteristics, but highly questionable politics. The article was utterly unpersuasive, but in the end, I reluctantly voted for Johnson because Goldwater was too conservative for my political tastes.

Goldwater went back to the Senate, where he served with great distinction and high personal morality. Johnson got us deeply into an unwinnable war in Vietnam that hurt our nation and claimed more than 58,000 American lives. The more than 1,100 psychiatrists, it turned out, were wrong in their diagnosis and predictions.

The misdiagnosis of Goldwater should surprise no one, since none of the psychiatrists had ever examined, or even met, the Arizona senator. They just didn’t like his politics. Indeed, some feared that he would destroy the world if he had access to the nuclear button.

The most powerful TV ad against Goldwater showed an adorable young girl playing with a flower. Then, the viewer hears an ominous voice counting down from 10, the camera zooms into a tight close-up of the little girl’s eye, and you see the horrific mushroom cloud of a nuclear explosion, implying that electing Goldwater would bring about a nuclear holocaust. It was an effective ad. It influenced me far more than the psychobabble in the Fact article.

Following the Goldwater-psychiatrist debacle, the American Psychiatric Association declared it to be unethical for a psychiatrist to offer any kind of a diagnosis on a public figure without having examined that person.

Now, more than half a century later, numerous psychiatrists and other mental health professionals are violating that sound ethical principle by diagnosing President Trump, who they have never examined. They are offering diagnoses, ranging from Alzheimer’s to narcissistic personality disorder to paranoia and more. This is irresponsible, in my view.

We should continue to debate the merits and demerits of President Trump’s policies, effectiveness, personality and other factors that are relevant to his presidency. Those who oppose the president are of course free to criticize him, to work for the election of a Democratic Congress in 2018, and to support another candidate for president in 2020. That’s how democracy works.

But let’s leave diagnoses to doctors who have examined their patients and not remove a duly elected president of the U.S. from office on amateurish speculation that he is mentally incapable of functioning in office.

Alan Dershowitz (@AlanDersh) is a contributor to the Washington Examiner's Beltway Confidential blog. He is the Felix Frankfurter Professor of Law, Emeritus, at Harvard Law School and author of "Trumped up! How Criminalizing Politics is Dangerous to Democracy." This article was originally published by Fox News.

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