Born in 1926 in Victoria, B.C., Copan moved to the mainland in 1935. In 1942, at nearly 16 years of age, he enlisted in the Canadian Navy. Returning safely from World War II, Copan worked at a variety of labour jobs, before being employed as a longshoreman by the British Columbia Maritime Employers Association (BCMEA) in 1953. He worked primarily for three companies that operated under the umbrella of the BCMEA, including Canadian Stevedoring, Empire Shipping Company, and Western Stevedoring Company Limited. Employment on the waterfront meant being versatile, and Copan was trained in many different positions. These included lift truck operator, winch operator, hatch tender, checker, bull dozer operator, front end loader operator, wheat machine operator, dock gantry crane operator, switchman, locomotive engineer, straddle carrier, and linesman. In 1965 Copan became active in the International Longshore and Warehouse Union, and was elected president of Local 501 the next year. He also served on the executive of the Canadian Area section of the same union, serving as vice-president and in 1979, as president. Leslie Copan retired in 1988.