The Justice Department saw Du Bois’s petition as a threat to national security. They thought it was communist propaganda meant to encourage American pacifism in the face of Soviet aggression. They put Du Bois on trial in order to brand him as “un-American,” to use the language of Joe McCarthy’s House Un-American Activities Committee. Du Bois was not in fact a Soviet agent. He was an American citizen using his First Amendment rights to protest nuclear weapons on his own behalf. A federal judge acquitted him because prosecutors failed to present any evidence.