Another partner Richard Gladstein defended its union leader Harry Bridges in deportation hearings three times from 1938 to 1955.
[6] In 1934, Andersen defended Ida Rothstein, an alleged communist leader of the San Francisco Bay area.
[5][10] In 1944, Andersen and his firm defended a "Negro" respondent on behalf of African-American workers who were members of the International Brotherhood of Boilermakers, Iron Shipbuilders and Helpers of American Union.
[4] In 1948, Andersen and his law firm represented two unions in decisions made by the National Labor Relations Board (NLRB).
[12] In the 1950s, Andersen represented Roy Hudson (union liaison and executive of the CPUSA), Donald Niven Wheeler (New Deal government official and alleged Soviet spy), Paul Schlipf (legislative assistant for the California State CIO), and Paul Chown (field organizer for the United Electrical, Radio and Machine Workers of America or "UE" union).
[13] In 1954, Andersen submitted an amicus curiae in VINCENT W. HALLINAN for Disbarment of Member of State Bar of California.
[3] In 1931–32, Andersen joined Carol Weiss King and others in founding the International Juridical Association (IJA), a legal bureau to help defend Communists in the USA.