"I don't know how they can retain their lawyer status, in the comments that they're making," Pelosi told reporters in the Capitol.
The exception, said Dershowitz, an opinion contributor to The Hill, would be cases where the conduct violated a specific law.
The Democrats' two impeachment articles, charging Trump with abuse of power and obstruction of Congress, fall outside the federal criminal code.
Pelosi on Thursday accused Trump's Republican allies of trying "to dismantle the Constitution" in their defense of the president.
Democrats have argued for the new information, noting that every other Senate impeachment trial in the nation's history has featured witnesses.
A wildcard in that debate is John Roberts, the chief justice of the Supreme Court who's presiding over the Senate trial.
Pelosi on Thursday said a Senate vote to acquit Trump would be invalid without calling new witnesses. »