The precautionary principle, the polluters pay principle and similar principles have become embedded in the language of contemporary environment policy. In this important new study, leading European experts in environmental law consider the legal significance of such environmental principles, both in jurisprudential theory and in practice before the courts. The development of the principles within the European Treaty is considered as well as the approach of the European Court of Justice to their interpretation. But it is the interpretation of environmental principles in front of national courts within Europe that forms the heart of the study, with chapters covering a number of the key Europe jurisdictions. Are such principles raised in cases? How do judges apply them? Do they determine the outcome of legal disputes? The study, the first of its kind, presents a dynamic picture of environmental case law across Europe, and will be of importance to practitioners, advanced students, and those concerned with the future development of environmental law and policy.