Book excerpt: In the context of multiple crises, EU Energy and Climate policy is often identied as one of the few areas still exhibiting strong integration dynamics. However, this domain is not exempt from contestation and re-nationalization pressures. This collection seeks to understand those contradictory integration and disintegration tendencies by problematizing the notion of authority: When, why, and by whom is EU authority in Energy and Climate policy conferred and contested? What strategies are used to manage authority conflicts and to what effect? These questions are examined in some of the knottiest aspects of EU energy and climate policy, for example, the adoption of the landmark Governance of the Energy Union Regulation, the long-drawn-out attempts to complete the EU’s internal energy market, the struggle to achieve ambitious EU targets in renewable energy and energy efficiency beyond 2020, the blurring of economic and security instruments in external energy policy, or the heated discussions over the Nord Stream 2 gas pipeline. The chapters in this book were originally published as a special issue of the Journal of European Integration.