This book describes the unique process of legal evolution in the field of environmental law, which is denoted as constitutionalisation of the environmental protection in the EU legal order.This book describes the unique process of legal evolution in the field of environmental law, which is denoted as constitutionalisation of the environmental protection in the EU legal order. This notion refers to the process of transformation of this particular area of law, which is reflected in its novel autonomous features and materialised through the normative and jurisprudential elevation of environmental objectives and principles. In the course of recent years, environmental protection has evolved from a sectoral policy to one of the core, transversal principles of the EU legal order. Grasped through the prism of the principles of integration and coherence, the environmental protection has become all-present and influential aspect of EU legislation, while at the same time reaching the status of a fundamental value underlying the constitutional dimension of the European Union as a community of law. The book examines this process on the basis of comparative legal analysis, the current practice of EU institutions, and the recent case-law of the Court of Justice of the EU.