Those lawyers were demonized as I am being today. I have a thick skin, developed over many years of defending controversial and unpopular clients and causes. But I am concerned that young lawyers will be deterred from representing such clients and causes for fear it will destroy their careers. I am hearing that from young lawyers and students.

I said that if a president did something entirely legal, with a mixed motive that included his desire to be re-elected, that mixed motive could not turn a legal act into an impeachable offense. I also said that a good motive could not turn a criminal act into a lawful one.

Pictured: Alan Dershowitz speaks in the United States Senate during impeachment proceedings against President Donald Trump, on January 27, 2020. (Photo by Senate Television via Getty Images)

I grew up in the age of McCarthyism, when lawyers who represented suspected communists were blamed for the alleged sins of their clients. I never expected to see a return to that benighted time, especially by self-proclaimed progressives. But it's back.

I appeared on the Senate floor as constitutional counsel against impeachment, not as a regular, full time counsel for US President Donald J. Trump. As I said in my opening remarks: I come not as a partisan but to " defend the constitution" from partisan misuse. I laid out the constitutional arguments in an academic manner.

Instead of simply disagreeing with my scholarship or offering alternative interpretations of the operative constitutional terms, I was personally demonized, my motives questioned, and my integrity impugned. Even my qualifications as an expert in constitutional law were challenged, despite my having taught courses and seminars, written numerous books and articles and litigated large numbers of cases involving the constitution for more than half a century. None of this would have happened if I had appeared in the same capacity but in favor of Trump's impeachment (or against the impeachment of a Democratic President).

This hypocrisy of this double-standard — by political leaders, media pundits, academics and ordinary folks — is shameful, but done not only without shame but with self-righteousness. It was similar during the McCarthy era of my youth. Now as then, the "cause" — anti-Trumpism today, and anti-communism back then — were seen as so righteous that any means, no matter how unfair, is justified in achieving the end. Outright wilful lying is justified by anti-Trump zealots in the interest of getting rid of Trump.

Consider the way Democratic leaders and the anti-Trump media deliberate distorted what I said in response to a question about quid pro quo. I said that if a president did something entirely legal, with a mixed motive that included his desire to be re-elected, that mixed motive could not turn a legal act into an impeachable offense. I also said that a good motive could not turn a criminal act into a lawful one. These self-evident statements were turned into the lie that I had claimed a president could do anything — even kill his opponent or tamper with voting machines — as long as these felonies were motivated, supposedly in the public interest, by a desire to be re-elected. A CNN talking head, Joe Lockhart, said that what I advocated was comparable to the genocides committed by Hitler and Stalin.

These liars knew full well that what they were saying was demonstrably false but they also knew that if you repeat a lie often enough — on television or on the Senate floor — it will be believed, especially by those who want to believe it. And this lie has been repeated — by the anti-Trump media and Democratic leaders— so often that it is now taken as an incontrovertible truth by many. As a result, I have been demonized by many on the left who refuse to understand why a liberal Democrat would defend the constitutional rights of a controversial Republican president. This is the mirror image of the McCarthyism of my youth, when many on the right could not understand why anti-communist centrist lawyers would defend the rights of communists.

Those lawyers were demonized as I am being today. I have a thick skin, developed over many years of defending controversial and unpopular clients and causes. But I am concerned that young lawyers will be deterred from representing such clients and causes for fear it will destroy their careers. I am hearing that from young lawyers and students.

Demonizing defense lawyers for representing politically incorrect clients and causes is the true road to tyranny.