“You had to leave the realm of constitutional law scholars and go to criminal defense lawyers.”

.@AlanDersh is grossly misstating law, history, and even the arguments in the Johnson Senate impeachment trial. He’s not to be trusted. Trump’s mendacity has sadly rubbed off on my former colleague. Read my @washingtonpost op-ed laying it all out: https://t.co/QMcotKawIS

— Laurence Tribe (@tribelaw) January 20, 2020

No, in other words.  This is not the argument "Dersh" says it is:

“I am making an argument much like the argument made by the great Justice [Benjamin] Curtis, and to call them absurdist is to insult one of the greatest jurists in American history,” he said. “The argument is a strong one, the Senate should hear it. I am privileged to be able to make it,” Dershowitz said on This Week. “I have a limited role in the case. I’m only as counsel on the constitutional criteria on impeachment.”

Tribe's response:

As if to match one great justice with another, Dershowitz on Sunday cited Justice Benjamin Curtis, a dissenter from the infamous Dred Scott decision. Curtis, after stepping down from the court, represented President Andrew Johnson in the 1868 impeachment trial and, Dershowitz claimed, prevailed by insisting that abuse of power is not an impeachable offense.
That is false. They actually lost a Senate majority (and avoided by a single vote the supermajority needed to remove Johnson) only because one senator appears to have been bribed to vote for the president. And, so far as the arguments themselves were concerned, Dershowitz is also misrepresenting. The fact is that Curtis, in his opening statement representing the president, and Attorney General Henry Stanbery, in his closing statement, insisted both that Johnson had broken no valid law and that he had not abused his presidential powers in any way.

They objected to impeaching Johnson on the basis of his unsuccessful attempts to fire his secretary of war in violation of the Tenure of Office Act, arguing that Johnson hadn’t actually violated the act and that in any event was within his rights to deem it unconstitutional, as it ultimately was held to be. They objected to impeaching Johnson for the manner of his “executive administration.” They objected to impeaching him for having disgraced the office through his outlandish insults to members of Congress, arguing that doing so would undermine the “precious right … of free speech.”
But, far from viewing “abuse of power” as unimpeachable, the defense team in Stanbery’s closing took the opposite tack, saying of Johnson that he never misused “public money” or injured any “public officer” or “appropriated the public funds … unlawfully to his own use” but, rather, “stood firm as a rock against all temptation to abuse his own powers or to exercise those which were not conferred upon him.”

Rep. Schiff knows what he's doing:

“You had to go so far out of the mainstream to find someone to make that argument,” Schiff said on ABC’s This Week. “You had to leave the realm of constitutional law scholars and go to criminal defense lawyers.” Dershowitz argued that even if proven, abuse of power and obstruction of Congress do not add up to impeachable offenses. “The logic of that absurdist position that’s being now adopted by the president is he could give away the state of Alaska, he could withhold execution of sanctions on Russia for interfering in the last election, to induce or coerce Russia to interfere in the next one,” Schiff said about the argument.

I rather like that highlighted part.  And the proof Rep. Schiff, like Speaker Pelosi, is paying attention to the best available arguments:

From @AlanDersh’s 2018 book: “Assume Putin decides to ‘retake’ Alaska, the way he ‘retook’ Crimea. Assume further that [President Trump] allows him to do it ... That would be terrible, but [not] impeachable.” That’s really Trump’s legal position??????!!!@lisamurkowski take note!

— Laurence Tribe (@tribelaw) January 18, 2020