The Academy is an institution for the study and teaching of public and private international law and related subjects. Its purpose is to encourage a thorough and impartial examination of the problems arising from international relations in the field of law. The courses deal with the theoretical and practical aspects of the subject, including legislation and case law. All courses at the Academy are, in principle, published in the language in which they were delivered in the Collected Courses of the Hague Academy of International Law. This volume contains: - Means of Ensuring Compliance with and Enforcement of International Environment Law by R. WOLFRAM, Director of the Max-Planck Institute for Comparative Public Law and International Law. - The Formation of Customary International Law by M. MENDELSON, Professor at University College, London, UK.