The intolerance of the contemporary left in Western democracies appears to know no bounds. These days it’s all but impossible for a political conservative to be heard at many leading universities in Australia, Britain and the US — despite the fact that the academy is supposed to be a bastion for free expression.

And now the left is moving to silence those with whom it disagrees by what lawyer and former Harvard University professor Alan Dershowitz has termed the tactic of pathologising or psychiatrising political opponents.

Soon after Donald Trump ­defeated Hillary Clinton in the November 2016 presidential election, there were calls for his ­impeachment — even before the inauguration of January 2017. The American left is still banging this particular drum — despite the fact that, more than 12 months after the election, there is no evidence Trump ever engaged in high crimes and misdemeanours.

Even so, on ABC radio’s PM program on Tuesday, Linda Mottram gave a soft interview to Trump critic Jill Wine-Banks, who was engaged in the prosecution of Richard Nixon in the ­Watergate case in the 1970s.

Wine-Banks accused Trump of obstructing the course of justice. In her rush to political judgment, she is not even willing to await the result of special counsel Robert Mueller’s report. According to Wine-Banks, Trump should be impeached. Now. No other view was heard.

It’s possible that Wine-Banks found time to talk to ABC radio in Australia from Chicago ­because the “Impeach Trump” campaign has run out of some steam of late. It seems to have been overshadowed by the “Institutionalise Trump” movement.

This is all the rage following the publication of ­Fire and Fury, Michael Wolff’s book about the US President and his administration. Wolff is one of that breed of journalists who rely heavily on anonymous sources and who have scant regard for fact-checking. He also refuses to provide evidence in support of his assertions.

Wolff alleges that “one hundred per cent of the people around” Trump regard him as a “moron” and an “idiot”. And he quotes Steve Bannon, a disaffected former Trump adviser who was sacked last August, as saying that the President has “lost it”.

No surprise here. What is surprising is the entry into the debate of Yale University professor of psychiatry Bandy Lee. Last month, before the ­release of Fire and Fury, Lee ­addressed about a dozen members of congress on Capitol Hill. The names of the attendees have not been released.

Lee’s assessment was that Trump is “going to unravel”. In an interview, reported inPolitico, she said “the rush of tweeting is an ­indication of his falling apart under stress”.

Lee added: “Trump is going to get worse and will ­become incontrollable with the pressures of the presidency.” She is editor of The Dangerous Case of Donald Trump (Thomas Dunne Books, 2017), in which 27 psychiatrists and ­psychologists agree that the President is a clear and present danger to the US.

The line is that Trump should be removed from office under the constitution’s 25th amendment. This enables the Vice-President and a majority of cabinet members to advise the Senate and House of Representatives that the President is “unable to discharge the powers and ­duties of his office”. Whereupon the “Vice President shall immediately assume the powers and ­duties of the office as Acting President”.

It’s a big call and most unlikely to happen unless an incumbent suffers a debilitating illness or ­injury. Even so, Wolff and Lee are in the vanguard of the movement and have the support of many a Trump-hater.

Dershowitz is what in Australia we would call a social democrat. In view of this, it’s no surprise that he voted for Clinton in ­November 2016. And it’s also no surprise he is intent on upholding democratic values against attacks from the extreme left.

In an opinion piece on the Fox News website, Dershowitz has warned that it would be “dangerous” to American democracy to have Trump removed on the basis of alleged mental illness or ­dementia. He believes the President should be responded to, not silenced.

Also, based on his research and writing in the field of law and psychiatry, Dershowitz maintains that it is “unprofessional, unethical and absurd for any mental health professional who has not examined President Trump to offer a diagnosis or psychiatric prediction about him”.

This is the official position of the American Psychiatric Association, which introduced the Goldwater Rule 50 years ago after mental health experts unprofessionally and inaccurately assessed Barry Goldwater as unfit for office. Goldwater was the ­Republican candidate in the 1964 presidential election won by Democrat Lyndon Johnson.

Traditionally, the attempt to silence opponents by medical ­intervention has been a tactic of authoritarian and totalitarian ­regimes. It was used in the Soviet Union — as documented by Sidney Bloch and Peter Reddaway in their 1977 book, Russia’s Political Hospitals. In an article in Canada’s The Globe and Mail on ­December 22, 2017, Madeline Roache maintains that the practice continues in contemporary Russia under Vladimir Putin.

The US is not the old Soviet Union or the new Russia. But the argument is much the same. Some members of the left, in or out of office, are so intolerant of different opinions that they maintain only a madman or madwoman could disagree with them.

Columnist David Brooks ­acknowledged in The New York Times this week that Trump is not the “raving madman” depicted by his political opponents. The abuse of psychiatry is an abuse of democracy.

Gerard Henderson is executive director of The Sydney Institute