The president's lawyers have made the sweeping assertion that the articles of impeachment against President Donald Trump must be dismissed because they fail to allege that he committed a crime − and are, therefore, as they said in a filing with the Senate, "constitutionally invalid on their face."

Another of his lawyers, my former Harvard Law School colleague Alan Dershowitz, claiming to represent the Constitution rather than the president as such, makes the backup argument that the articles must be dismissed because neither abuse of power nor obstruction of Congress can count as impeachable offenses.

Both of these arguments are baseless. Senators weighing the articles of impeachment shouldn't think that they offer an excuse for not performing their constitutional duty.

The argument that only criminal offenses are impeachable has died a thousand deaths in the writings of all the experts on the subject, but it staggers on like a vengeful zombie. In fact, there is no evidence that the phrase "high Crimes and Misdemeanors" was understood in the 1780s to mean indictable crimes.

On the contrary, with virtually no federal criminal law in place when the Constitution was written in 1787, any such understanding would have been inconceivable. Moreover, on July 20, 1787, Edmund Randolph, Virginia's governor, urged the inclusion of an impeachment power specifically because the "Executive will have great opportunitys of abusing his power." Even more famously, Alexander Hamilton in Federalist 65 defined "high crimes and misdemeanors" as "those offenses which proceed from the misconduct of public men, or, in other words, from the abuse or violation of some public trust."

Any number of such violations of the public trust, such as working with foreign governments in ways that make the president beholden to their leaders, or cooperating with those governments to bolster the president's reelection, clearly must be impeachable even though they might violate no criminal law and indeed no federal statute at all.

The related suggestion that, even if some noncriminal offenses might be impeachable, "abuse of power" is not among them is particularly strange. No serious constitutional scholar has ever agreed with it.

Justice Joseph Story wrote in 1833 that there are "many" impeachable offenses, none of which is "alluded to in our statute book," because the abuses of power that constitute "political offences" are "of so various and complex a character, so utterly incapable of being defined, or classified, that the task" of enumerating them all through "positive legislation would be impracticable."

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."

The president is entitled to robust legal representation. But his lawyers should not be allowed to use bogus legal arguments to mislead the American public or the senators weighing his fate.

Laurence H. Tribe is the Carl M. Loeb University Professor of Constitutional Law at Harvard and the co-author, most recently, of "To End a Presidency: The Power of Impeachment."