This book is focused on the European Union (EU) Directive 2004/35/EC on environmental liability with regard to the prevention and remediation of environmental damage (Directive or ELD). As noted in successive chapters of this book, experience with the ELD in actual practice remains limited. A variety of legal, administrative, technical, and economic issues pertinent to the ELD and its implementation, which in some cases involve novel and complex considerations, are covered in this book. A first of its kind, this book provides background and guidance for persons seeking an in-depth discussion of critical ELD issues and insightful practical considerations for predictable and effective application of this regime. As such, this book provides concepts and tools for a holistic understanding of the ELD regime through contributions by diverse practitioners in both public and private sectors. In this Introduction, first, a brief summary of the ELD is provided, followed by a guide to the content of the book’s three main sections and their constituent chapters. This book is organised in three parts: (1) scope, substance, and procedure of the ELD; (2) emerging issues and practices in ELD application; and (3) the ELD’s future: tools, approaches, and further development. A preview of each section and its chapters is provided later in this Introduction. Summary: Adopted in 2004, the ELD makes Member States responsible for ensuring that damage to water, land, and biodiversity (protected species and habitats) is either prevented by appropriate measures in cases of imminent threats, or effectively remedied by restoring the previous condition if the damage has already been done. Member States were required to transpose and implement the ELD into their national legal systems by April 2007 and, as of 1 July 2012, all Member States had completed this transposition. The ELD creates an environmental liability regime aimed at preventing environmental damage pursuant to the ‘polluter pays principle’ and, should an incident occur, provides a framework for remediating such damage. The ELD outlines the types of damage and activities for which an operator may be held liable, as well as a limited set of exemptions where the ELD does not apply. Annex III of the ELD provides a specific listing of those occupational activities that trigger strict liability should an incident occur. Under the ELD, operators are to take preventive action in cases of immediate threats of environmental damage, and to remedy environmental damage if it has occurred. How, and to what extent, remediation of damaged resources is to be undertaken, including primary, compensatory, and complementary remediation, is outlined in Annex II of the ELD. The ELD also contains four additional annexes which provide further detailed information and/or direction as referenced in specific articles of the Directive. These annexes address criteria for determining significant environmental damage (Annex I), relevant international conventions (Annex IV), relevant international instruments (Annex V), and Member State reporting requirements (Annex VI). The full text of the ELD, including the annexes, is provided as an Appendix to this book. In implementing and transposing the ELD into national law, a series of issues and questions arises, including, importantly, determining which cases fall under the ELD and which do not; how the defences and/or exceptions provided in the ELD should be applied; the role of financial security; how the definitions of ‘significant’ environmental damage and ‘operator’ should be construed and applied; and how damage is best assessed and remediated. These and other critical issues are addressed in the chapters that follow