Department of Justice’s Office of Immigration Litigation where he represents the Attorney General and the Department of Homeland Security before the United States Circuit Courts of Appeals. Prior to joining the Justice Department, Professor Leo served on active duty as a commissioned officer in the Judge Advocate General’s Corps of the United States Navy where he specialized in criminal and international law. He maintains his affiliation with the Navy as a reserve Lieutenant Commander and in 2008 served as Deputy Chief for the Law and Order Task Force, Multi-National Force Iraq, Al Rusafa, Iraq. Professor Leo was also associated with a boutique litigation firm in Boston where his practice focused on construction litigation.