Treaty law imposes several limitations on the use of the European Union’s (EU’s) powers in the energy sector. While many of these energy-specific competence restrictions have been analysed in EU legal scholarship, the scope and interpretation ofEUcompetences in the area of trans-European energy infrastructures have remained unexplored. Addressing this gap in the literature, the article examines the division of powers in the EU energy sector in the light of the recent Aquind ruling. The analysis demonstrates that the Aquind case not only clarifies the division of powers with regard to EU energy law and the development of trans-European energy infrastructures but also highlights how Member States’ territorial sovereignty interacts with the development of those infrastructures and thus impacts the development of the internal energy market.