Career
Born in Ottawa, Illinois, Cassidy received his law degree from the University of Notre Dame and in 1917 and was admitted to the Illinois bar also in 1917. Cassidy served in the United States Army in Europe during World War I. In 1920, Cassidy moved to Peoria, Illinois to head the legal department of Aetna Life Insurance Company. In 1921, he set up his own law firm in Peoria.
Cassidy was involved with the Democratic Party.
Cassidy was appointed Illinois Attorney General in 1938 and served until 1941. Cassidy died in a hospital in Peoria, Illinois.
