Exercise of EU Competences and Pre-emption of Member States’ Powers in the Internal and the External Sphere: Towards ‘Grand Unification’?

The exercise of EU competences imposes constraints on Member States’ law-making powers (‘internal-sphere pre-emption’) and on their treaty-making powers (‘external sphere pre-emption’). Legal scholarship has extensively analysed external sphere pre-emption and has paid increasing attention to internal-sphere pre-emption. Can a ‘Grand Unification’ theory account for the pre-emption phenomenon in both spheres? To answer that question, the article examines, in each sphere, the function, nature, and scope of pre-emption, as well as the framework the ECJ applies for pre-emption analysis. The examination reveals similarities and differences, discussed in the article’s conclusion.