My dissertation is a legal-historical study of the prosecutions of Holocaust deniers Ernst Zündel and James Keegstra in the 1980’s and their appeals to the Supreme Court of Canada in the early 1990’s. I also explore human rights proceedings and related civil actions initiated against Zündel after his conviction was overturned by the SCC in 1992 until his deportation to Germany in 2005. The primary objective of my research is to assess what these legal proceedings and their impact on the Jewish community tell us about the limits of the criminal sanction and other regulatory measures as a means for protecting vulnerable communities from harmful speech. My dissertation examines the Keegstra and Zundel cases from the perspective of Canadian Jews. Rather than revisiting the question of whether philosophy or constitutional rights suggest that criminal law should or should not forbid hate speech and under what conditions, I ask: assuming that hate speech harms vulnerable groups and pollutes our discourse, what can history tell us about the law’s ability to combat it?