In this paper, we examine the treatment of extremist speech by the leading human rights courts in the US & Europe. Post-war European advocates of “militant democracy” urged state limitation of speech challenging fundamental tenets of the democratic order, and the comparative free expression literature often treats US courts as outliers in their refusal to accept such limitations. We assess this characterization via comparative examination of the treatment of extremist speech by the US Supreme Court & European Court of Human Rights. In particular, we examine all First Amendment/Art. 10 judgments involving extremist speech to assess whether the US Court has departed from the Strasbourg Court in extending robust protection to such speech, and if so, when that protection emerged and whether it has extended equally to different varieties of extremism.