Frank James (Jim) Sensenbrenner, Jr. (born June 14, 1943) is an American politician who has been a member of the Republican Party in the United States House of Representatives since 1979, representing Wisconsin's 5th congressional district (map). The district, the state's richest, includes many of Milwaukee's northern and western suburbs, and extends into rural Jefferson County. It was numbered as the 9th District until 2003.
He is the former Chairman of the House Science Committee and the former Chairman of the House Judiciary Committee; when the Republicans lost control of the House, he finished his six-year term as Chairman, and was not able to be chosen as the Judiciary Committee's ranking minority member (that honor went to Lamar S. Smith of Texas). He served as the Ranking Republican on the House Select Committee for Energy Independence and Global Warming from 2007 to 2011, when Republicans abolished the committee after regaining control of the House.