In 1949 he was nominated for the Writers Guild of America Award for Best Written American Western for his work on Green Grass of Wyoming.
He told the committee that people in his role could not work Communist propaganda into scripts without it being noticed by film producers and studio executives.
[9] He painted a particularly negative portrait of writer John Howard Lawson as the "grand Poo-Bah of the Communist movement" who "speaks with the voice of Stalin and the bells of the Kremlin.
"[10] Berkeley was represented by Edward Bennett Williams, who had close ties to many enthusiasts of the anti-Communist campaign of the McCarthy era.
[4] Following his testimony, Berkeley became a member of an organization formed to expose Communist influence in the entertainment industry, the Motion Picture Alliance for the Preservation of American Ideals (MPA).