The new lawyers include Harvard Law professor emeritus Alan Dershowitz, Clinton-era special prosecutor Ken Starr and Robert Ray, Starr's successor at the Office of Independent Counsel during the Clinton administration.
They will join a team led by White House counsel Pat Cipollone (the successor to Don McGahn) and external attorney Jay Sekulow, who also was a key player on the team of lawyers that represented Trump during the Mueller probe. Both Sekulow and Cipollone are still expected to deliver statement's on Trump's behalf from the Senate floor after the trial opens on Tuesday.
Some of the new additions have been rumored since shortly before the House voted to impeach the president last month.
Dershowitz confirmed the news - or at least confirmed that he would be joining the team - in a series of tweets: