Released on bail, Hall rose to the secretariat of the CPUSA. When the Supreme Court upheld the Smith Act (June 4, 1951), Hall and three other men skipped bail and went underground. Hall's attempt to flee to Moscow failed when he was picked up in Mexico City on October 8, 1951. He was sentenced to three more years and eventually served over five and a half years in Leavenworth Federal Penitentiary. In prison he distributed party leaflets and lifted weights. He was located in a cell adjacent to that of George Kelly, a notorious gangster of the prohibition era. The Supreme Court of the United States later reversed some convictions under the Smith Act as unconstitutional.