David Boies, the lawyer whose firm until recently represented Virginia Giuffre in her libel suit against retired Harvard professor and attorney Alan Dershowitz, sued Dershowitz for defamation in New York County Supreme Court on Thursday.

Giuffre is one of the women who says she was trafficked by billionaire Jeffrey Epstein as a teenager. She says Epstein and other men, including Dershowitz, sexually abused her. Dershowitz filed counterclaims against Giuffre in the Southern District of New York this week, denying all her claims and accusing her of defamation.