practicing with a specialization in criminal law. From 1965 until 1968 he served as a member of the New York State Senate, in that time working with Senator Robert F. Kennedy to establish the Bedford Stuyvesant Restoration Corporation and chairing the Joint Legislative Committee on Child Care Needs, sponsoring over 25 bills that would be signed into law. From 1969 until 1973, he served on the New York City Council.
Thompson joined the bench when he was elected as a Justice of the Supreme Court in 1974. He was designated to the Appellate Term in November of that year, and in 1978 he was appointed Assistant Administrative Judge for Brooklyn and Staten Island. Justice Thompson was designated by Governor Hugh Carey to the Appellate Division, Second Department in 1980. He retired in 2001 after over twenty years on the bench, and joined National Arbitration and Mediation, where he was named one of the top ten mediators in New York State in 2010 and 2011 by a New York Law Journal Reader Rankings Survey.
In addition to his distinguished legal, political and judicial career, Thompson was a member of the American and Brooklyn Bar Associations, the Metropolitan Black Bar Association Three Hundred and Ninety and served on the New York State Commission on Judicial Conduct from 1990 until 1998. He is a former regional director of the NAACP, director of Bedford Stuyvesant Restoration Corporation and other organizations, and co-chairman of Confidence in the Legal System, Committee to Promote Public Trust, and Not Just Blacks and Jews in Conversation. He served as a sergeant in the 92nd Infantry Division in Italy during World War II, earning three battle stars, a combat infantry badge and the purple heart.
Appellate Division, Second Department, 100th Anniversary. 22. The Historical Society of the Courts of the State of New York, 1996. Web. 3 Aug. 2012. http://www.courts.state.ny.us/history/pdf/Library/Courts/App_Div_Sec_Dept_100th_Anniv.pdf
"Hearing Officer Resume: Hon. William C. Thompson (Ret.)." National Arbitration and Mediation. Web. 3 Aug. 2012. http://www.namadr.com/documents/ho_resumes/NAMResume-Thompson_William.pdf