After the war, Hammett returned to political activism, "but he played that role with less fervour than before". He was elected president of the Civil Rights Congress (CRC) on June 5, 1946, at a meeting held at the Hotel Diplomat in New York City, and "devoted the largest portion of his working time to CRC activities".
In 1946, a bail fund was created by the CRC "to be used at the discretion of three trustees to gain the release of defendants arrested for political reasons." Those three trustees were Hammett, who was chairman, Robert W. Dunn, and Frederick Vanderbilt Field, "millionaire Communist supporter." On April 3, 1947, the CRC was identified as a Communist front group on the Attorney General's List of Subversive Organizations, as directed by U.S. President Harry S. Truman's Executive Order 9835.