Lawyers for James “Whitey” Bulger urged a federal appeals court to order the judge overseeing the reputed gangster’s upcoming trial to step aside, saying the jurist’s ties to the FBI and the Department of Justice present a strong bias and conflict of interest in the case.

The lawyers said they plan to call US District Court Judge Richard G. Stearns as a witness in the long-anticipated trial, and that his ties to prosecutors and his own interest in the case would influence any impartial jury.