Margolis's parents had escaped the anti-Semitism of their native Russia by coming to New York City. Eventually, they were financially able to move to Santa Barbara, California, where their son decided upon a legal career. He studied law in San Francisco and practised there, later moving to Los Angeles; in both cities, he specialised in cases involving civil rights and labour disputes.
After successfully fighting the deportation of Harry Bridges, the Australian-born leader of the Longshoremans' Union, Margolis gained further attention in 1944 in the controversial "Sleepy Lagoon" murder case. Two years earlier, a large group of "zoot- suited" young Mexican-Americans had been rounded up and accused of the brutal murder of a fellow Hispanic near a Los Angeles reservoir nicknamed "Sleepy Lagoon". Margolis accused the police of racism in denying the defendants the right to consult their attorneys, and won an historic reversal of their convictions.
In 1947, when the Oscar-winning screenwriter Ring Lardner Jnr and nine other left-wing writers, producers and directors received subpoenas from the newly revived House on Un-American Activities Committee (HUAC), the film-makers badly needed someone courageous enough to advise them. Margolis's name, said Lardner, "just automatically came up if you were involved in a civil liberties case". Despite Margolis's strenuous efforts, the "Hollywood 10", who had refused to reveal their political affiliations, were convicted of contempt of Congress, and duly fined, imprisoned and blacklisted.
In 1951 Margolis and his fellow attorney Robert W. Kenny defended the Communist screenwriter Paul Jarrico when he too faced the HUAC interrogators. While Jarrico was indignantly telling the committee that history would rank the stand of the blacklisted screenwriter against his accusers alongside the stand of Thomas Jefferson against the English sedition laws, Kenny was hissing "Take it easy! Take it easy!" into his left ear, and Margolis was hissing "Give it to 'em! Give it to 'em!" into his right ear. (Jarrico was blacklisted until 1968.)
In 1951, Edward Dmytryk, the film director who had been one of the "Hollywood 10" four years earlier, returned to Washington and appeared as an extremely co-operative witness. As well as naming 26 people as subversives, Dmytryk told HUAC that he had attended a Communist committee meeting at the home of Margolis, and that the attorney had been the host.
After HUAC's chairman J. Parnell Thomas was convicted of misappropriating government funds and sent to the same prison where two of the "Hollywood 10" were incarcerated, Georgia's John S. Wood succeeded Thomas. Between 1951 and 1952 Chairman Wood conducted an exhaustive ten-part investigation into reds in the entertainment industry.
In 1952 Margolis received a subpoena, ordering him to testify before HUAC. "I'll fry in hell before they get any information out of me about my clients," he told friends and colleagues. He stayed true to that vow during this testimony, refusing to answer questions about private political beliefs. When Wood rebuked him for his "contemptuous attitude", Margolis replied, "I feel nothing but contempt for this committee. You have no right to tell people how to think."
In 1958 Margolis and Robert Kenny again joined forces to represent 23 former film-makers who sued the Hollywood studio for $56m. The two attorneys told the United States Supreme Court that their clients, who had invoked the Fifth Amendment to protect themselves from self- incrimination, had been unconstitutionally blacklisted. The suit was dismissed.
That same year, Margolis represented Oleta O'Connor Yates, a California Communist who had refused to inform on fellow party members in cross-examination, and had been sent to prison for criminal contempt. Margolis succeeded in having Yates's sentence set aside. The following year HUAC named Margolis and 38 other lawyers as members of "an elite corps" who were supporting Communism.
In December 1974 the American Civil Liberties Union in Los Angeles gave a dinner to honour the "Hollywood 10", Robert Kenny and Ben Margolis.
Ben Margolis, lawyer: born New York 23 April 1910; married (three sons); died Portland, Oregon 27 January 1999.Reuse content