Gibson, Dunn & Crutcher is representing Perkins Coie as the law firm seeks to protect attorney-client privilege claims over its work with Democrat-linked groups ahead of the 2016 election.

Special Counsel John Durham, who is investigating the beginnings of the FBI’s Russia investigation, has challenged privilege claims from Perkins Coie over documents that prosecutors say could otherwise be used as evidence in an upcoming trial against the firm’s former partner, Michael Sussmann. Sussmann is accused of lying about his client representations during a 2016 meeting with the FBI about allegations of Trump’s ties to Russia.