This book analyses the case-law of the European Court of Justice on free movement in the energy sector. Sirja-Leena Penttinen provides a comprehensive review of the interpretation and application of the free movement provisions in the energy sector by the European Court of Justice (ECJ), which allow for cross-border energy trade (free movement of goods) and energy investments (free movement of capital). Through detailed analysis of ECJ case-law, Penttinen tracks the development of the legislative framework at EU level in response to the growth of the energy sector, as well as exposing the various political and economic nuances at play. In addition, she sheds light on the dynamic relationship between the EU Member States and their regulatory autonomy, the EU legislator, the Commission and the Court in the establishment of the EU internal energy market. Taking a coherent, systematic approach, this volume will be of great interest to scholars of EU law and energy policy, as well as policymakers and professionals working in this sector.