Judge Nathan Marks is the presiding judge over the trial of Joanne Sullivan. Marks breaks procedure by outright sabotaging the case against the D.A.s, as well as sexually harassing Ross and declaring fictitious contempt charges on Ross and McCoy to fine and arrest them.
Eventually, Schiff, a former colleague of Marks, successfully lobbied to remove him from the trial. After Joanne was convicted, Schiff voiced his bafflement over how Marks deviated from his own strong position on the law without rhyme or reason. (L&O: "I.D.")