Unconstitutional Constitutional Amendments in European Union Law: Considering the Existence of Substantive Constraints on Treaty Revision

The issue of unconstitutional constitutional amendments is extremely topical in the field of national and comparative constitutional law. In a recent article (2013), Roznai signals that ‘the global trend is moving towards accepting the idea of limitations—explicit or implicit— on constitutional amendment power’. But what about the ‘supranational’ EU? Would there be room to argue that substantive limitations of amendability—explicit or implicit—also exist as regards the EU Treaties? Furthermore, if so, would the Court of Justice of the European Union (CJEU) have the competence to enforce such limits? These questions are the central focus of this article. We argue that accepting the idea of substantive requirements of Treaty revision may be one of the next important steps in the ongoing process of EU constitutionalisation. In the first part of the article, we explore what kind of arguments are being used to justify a doctrine of unconstitutional constitutional amendments in national systems. Next, we ascertain to what extent such arguments can be used to justify a doctrine of unconstitutional constitutional amendment in EU law. In conclusion, we argue that it is quite conceivable that certain EU Treaty amendments would indeed be deemed to be a violation of the Treaties. Moreover, we contend that it is not unimaginable that the CJEU will assume the power to substantively review amendments to the EU Treaties, in cases where the Member States would choose to put forth suspect revisions to these documents.