 A member of the Republican Party, Cooper started working in 1981 in the Civil Rights Division of the U.S. Department of Justice in Washington, DC.In 1985 he was appointed as an Assistant Attorney General in the Office of Legal Counsel, United States Department of Justice during the Reagan administration.This is the office responsible for providing legal opinions and informal advice to the White House, the Attorney General, and Executive Branch Departments and Agencies on issues covering the full spectrum of statutory, regulatory, constitutional, and international law.