Unconstitutional criminalization

May criminalization constitute a violation of a constitutional right? This question has rarely been discussed directly in the legal literature. This Article offers a novel and fully developed normative framework for courts to review the constitutionality of substantive criminal law. It suggests a distinction between extra- and intra-constitutional approaches, offers a critique of existing approaches, and proposes a new intra-constitutional approach to the distinction between criminal offenses that may constitute an infringement upon constitutional rights and those that do not. The Article suggests that a constitutional right against criminalization may apply (and only apply) to activities that have substantive positive social value and do not impose any substantive social harm. The Article recommends some criteria for applying this framework.