He founded the Toronto-based Marxian Educational League which was a branch of Lovestone's Communist Party (Opposition) and the International Communist Opposition. The M.E.L. affiliated with the Ontario CCF in 1933. He was the M.E.L.'s delegate at the national Cooperative Commonwealth Federation convention that drafted the Regina Manifesto in 1933. Moriarty remained a member of Lovestone's international tendency until his death in 1936.
