Fred H. Moore was a socialist lawyer and the defense attorney of the controversial Sacco and Vanzetti case. He had collaborated in many labor and Industrial Workers of the World trials. He played a minor role several celebrated I.W.W. trials, including the Los Angeles Times bombing case in 1911 and the trial of Ettor-Giovannitti case, which arose from the 1912 Lawrence, Massachusetts, textile strike. Following acquittal in the Ettor-Giovannitti case, Moore spent the next several years roaming the country defending I.W.W. organizers. He was involved in the Centralia Massacre trial and the mass prosecution, on charges of sedition, of the I.W.W. in Chicago in 1918. Errors in a later trial, however, led Big Bill Haywood to demand Moore's resignation as I.W.W. attorney in 1920. Moore's career was revived by his hiring to head the defense team for Sacco and Vanzetti in the summer of 1920.
Many Italians involved with the defense of Sacco and Vanzetti were suspicious of Moore from the start, but they desperately needed a lawyer, any lawyer. "We didn't know what to do," said Aldino Felicani, head of the Sacco-Vanzetti Defense Committee. "We were just in despair." Arriving in Boston and meeting with the two defendants, Moore immediately saw the case as more than a murder trial. The uncompromising anarchists Sacco and Vanzetti, Moore realized, had the potential to spark an international cause celebre. While preparing his courtroom case, Moore began alerting labor and socialist organizations in America and Europe, thus setting the stage for the worldwide attention the two men would later draw.
But Moore's style annoyed more than the Defense Committee. Unkempt and utterly indifferent to decorum, he inspired little confidence in his clients. Sacco came to loathe Moore, and Vanzetti later regretted hiring him. Their fears were borne out in court, where Moore proved both incompetent and inflammatory. In the steamy courtroom, he frequently took off his jacket, and once, his shoes, enraging Judge Webster Thayer. Thayer routinely denied Moore's motions and lectured the California-based lawyer on how law was conducted in Massachusetts. Thayer once told reporters that "No long-haired anarchist from California can run this court!"