Here's part of the article you linked:

But last December, Mr. Dershowitz was drawn into the Justice Department lawsuit in an entirely different way. In a motion filed that month, Ms. Giuffre claimed that she and Mr. Dershowitz had sex when she was a minor aboard Mr. Epstein’s plane and at the money manager’s homes in New York, New Mexico and the Virgin Islands. She also asserted that Mr. Epstein had “sexually trafficked” her to other powerful friends, including Prince Andrew, the Duke of York. Buckingham Palace rejected the claims against the prince.

The judge later struck Ms. Giuffre’s motion from the court filing, but by then, the accusations were being widely reported and broadcast. Mr. Dershowitz’s phone was ringing with calls from reporters seeking comment. At every opportunity, he called Ms. Giuffre’s claims “outrageous falsehoods” and called the lawyers who had made the filing, Mr. Edwards and Mr. Cassell, “villains” who helped fabricate the claims against him.

Mr. Dershowitz said he would seek to have them disbarred, adding he had diary records and other information to show he was not at locations where Ms. Giuffre claimed they had met. “They’re prepared to lie, cheat and steal,” Mr. Dershowitz said in an interview on CNN in January.

The two lawyers, who declined to be interviewed for this article, filed a defamation lawsuit against Mr. Dershowitz, who responded with his own counterclaim.

Dershowitz was able to corroborate his version of his events, and Roberts was unable to corroborate hers, as I understand it, which is why the attorneys dropped their suits against each other.