This chapter, which discusses the difficult issue of defining ‘environmental law’ for the purposes of this book, covers the definition of certain key terms and provides an outline of some of the underlying themes that will be found in many of the chapters that follow. It is designed for use at the very beginning of a course of study to help to establish a context for future study. The notes and questions at the end of the chapter are designed to provoke thought about the way in which law and policy might affect everyday environmental issues and problems. In identifying the subject matter of this book, it is first necessary to consider whether there is any identifiable subject that could be termed ‘environmental law’.