This article is built around three general observations. The first is that, in the current stage of the development of constitutional theory and practice, there is a need to create procedures allowing the review of constitutional amendments. The second is that traditional mechanisms, in particular the “internal” review of constitutionality of constitutional amendments, may not always be able to provide sufficient protection against amendments that run counter to the existing constitutional structure. The final observation is that, in the current state of globalization, international law—in particular international human rights law—may play a significant role in an “external” assessment of the legitimacy of constitutional amendments. This role of international law is particularly well developed in Europe, and most of our conclusions therefore focus on the European perspective. Given the universal nature of human rights, however, at least some of these conclusions may also be validfor other regions of the world.