Cross-boarder and transnational legal issues concerning the environment are proliferating at such a fast rate that the international environmental law regime is in a continual state or rapid evolution. Here is a new edition of a major legal guide to the field, thoroughly updated and expanded to cover important emerging issues. New material includes an analysis of and commentary on non-state actors, new legal techniques of environmental protection, and development in the relationship of trade and the environment. This new edition also focuses on the trend toward more efficient enforcement of international environmental obligations.