Schabas was born in Cleveland, Ohio, with strong roots in an Ashkenazi Jewish background, though his family name, which is a variation of the Yiddish word for "Sabbath" ("Shabbos" in Yiddish, derived from "Shabbat" in Hebrew), has been interpreted as perhaps suggesting also a Sephardic connection [REF].
Schabas moved with his family to Toronto in 1952 and received his B.A. and M.A. degrees in history from the University of Toronto, and LL.B., LL.M. and LL.D. degrees from the Université de Montréal.