It is no longer news that there are countries in which it is unlawful to deny the existence of the Nazi Holocaust. Nor is it surprising that among these countries are Austria, Germany, and Israel, given the obvious historical reasons for their treatment of Holocaust denial with special sensitivity. But Holocaust denial is also a crime in Belgium, Canada, France, Spain, and Switzerland, among other countries, and a similar prohibition is now being proposed in Argentina. Moreover, existing or proposed laws also deal with denial of genocide in, for example, Armenia and Rwanda, and thus it is safe to say that the question of legal prohibitions on Holocaust denial is one of worldwide and not just regional or local interest.

Although the criminalization of Holocaust denial is thus hardly unique, it is also the case that in other countries, most obviously, but not only, the United States, the very idea of punishing the expression of an idea on account of the idea's falsity goes to the heart of principle of freedom of speech. It is not simply that Holocaust denial is legally permitted and constitutionally protected in the United States. It is that the legal and constitutional permissibility of Holocaust denial is understood as a core and not merely a fringe application of the very idea of freedom of speech under the First Amendment.