James Caesar Petrillo was born in Chicago, Illinois. In his youth Petrillo played trumpet (reportedly not particularly well), but made a career out of organizing musicians into the union starting in 1919.
Petrillo became president of the Chicago local of the musician's union in 1922, and was president of the American Federation of Musicians from 1940 to 1958. He continued being the prime force in the Union for another decade; in the 1960s he was head of the Union's "Civil Rights Division", which saw to the desegregation of the local unions and the venues where musicians played.
Petrillo dominated the union with absolute authority. His most famous actions were banning all commercial recordings by union members from 1942 - 1944 and again in 1948 to presure record companies to give better royalty deals to musicians; these were called the Petrillo Bans.
James Petrillo died at the age of 92.