The U.S. Justice Department’s second-in-command, Deputy Attorney General Jeffrey Rosen, will don the customary swallow-tail morning coat Wednesday for his debut argument at the U.S. Supreme Court.

President Donald Trump tapped Rosen, a former Kirkland & Ellis senior partner, to be the department’s chief operating officer in February 2019. Rosen will represent the United States as a friend of the court in Lomax v. Ortiz-Marquez, a case in which a Colorado prisoner has asked the justices whether a dismissal without prejudice for failure to state a claim counts as a strike under the Prison Litigation Reform Act.