sopinka was born in broderick, saskatchewan and lived there until his family moved to hamilton, ontario. he completed secondary school at saltfleet high school in stoney creek. he earned bachelor of arts and bachelor of laws degrees at the university of toronto. while studying law, he also played professional football. he was drafted in the sixth round of the 1955 cfl draft. he played with the toronto argonauts (1955 to 1957, 29 games) and then the montreal alouettes (1957, 8 games) of the canadian football league.