INTRODUCTION

When I began my research in this field a few years ago I assumed, like many writing about international environmental law, that the Trail Smelter dispute would provide a useful starting point from which to assess the framework of accountability that existed in international law for transboundary air pollution damage. The Tribunal's famous pronouncement, “that under the principles of international law, as well as the law of the United States, no state has the right to use or permit the use of its territory in such a manner as to cause injury by fumes in or to the territory of another or the properties of persons therein, when the case is of serious consequence and the injury is established by clear and convincing evidence,” had in many ways irrevocably confirmed that transboundary environmental damage, and specifically transboundary air pollution, entailed state responsibility.

The precedential value of this passage had been acknowledged in diverse contexts such as water disputes, pollution of the seas, and in various neighbourhood disputes between European States, as well as in the extensive literature that proliferated in the period after the Stockholm Conference on the Human Environment. It substantially informed the work of the International Law Commission on the Non-Navigational Uses of International Watercourses, and on Liability for Injurious Consequences of Acts not Prohibited by International Law. It also was unequivocally endorsed, either directly or in form, in the many environmental treaties that were enacted in the wake of the Stockholm Conference.