This paper will defend Kelsen‘s claim that formal constitutionality is reducible to material constitutionality. It will do so by discussing the question whether it is possible for a written constitution to limit judicial review of constitutional amendments to purely procedural review. There are several cases where such limitations broke down in practice. It will be shown that these apparent instances of judicial overreach were inevitable, in light of the reducibility of formal to material constitutionality first diagnosed by Kelsen, and that they should be welcomed by proponents of democratic constitutionalism.