A leading expert on election law, Professor Lowenstein has represented members of the House of Representatives in litigation regarding reapportionment and the constitutionality of term limits. While working for California's Secretary of State, Edmund G. Brown Jr. in 1971, he specialized in election law, and was the main drafter of the Political Reform Act,an initiative statute that California voters approved in 1974, thereby creating a new Fair Political Practices Commission. Governor Brown appointed Professor Lowenstein as first chairman of the Commission. He has served on the national governing board of Common Cause and has been a board member and a vice president of Americans for Nonsmokers' Rights.