He was born Schmil Kogan in Tomashpil, Ukraine, in 1906 and immigrated to Canada in 1924, living in Winnipeg and Regina before settling in Montreal in 1925.
In 1942, following the German invasion of the USSR, those party leaders who had gone underground, including Carr and Tim Buck, turned themselves in to the authorities.
[1][2] In 1946, after a cypher clerk in the Soviet embassy in Ottawa, Igor Gouzenko, defected to Canada,[clarification needed] a warrant was issued for Carr's arrest and he again fled to the United States.
In 1949 he was found guilty of conspiracy to obtain a false passport, and was imprisoned for seven years.
[1] By the time of his release from prison, Carr was no longer a member of the Labor-Progressive Party, but became active in the left wing organization United Jewish Peoples' Order (UJPO) until his death in 1989.