Foreword

by Prof. (em.), Dr. Dr. Dr. h.c. mult. Georg Ress

Former Judge of the European Court of Human Rights Member of the Institute of International Law

This commentary is devoted to one of the most important areas of international law, that is, international treaty law. In the past there have been intensive discussions and debates about a rank between the di erent sources of international law, and communist States have tended to accept only international treaties as really binding for them. This tendency has underlined the importance of international treaties as, from a political point of view, the most important source of international law. The consensus of States to be bound by an international treaty continues to play the primordial role in international law. Nevertheless, there are the underlying rules of customary law in the area of treaty law, to which the Commentary devotes an introductory chapter. At least the rules of customary international law will continue to govern questions not regulated by provisions of the Convention.

One need not mention the enormous amount of universal and regional multilateral treaties which intend to codify more and more areas of international law such as humanitarian law, the law of war, environmental law, human rights—to name only a few of the most important fields. This process of codification through international treaties has not only formalised international law and brought it closer to, and made it more appropriate for, international adjudication; it has also brought to the surface many similarities to the di erent codes of national law.

The present commentary on the provisions of the Vienna Convention on the Law of Treaties is, therefore, devoted not only to one of the most important but also one of the most complex subjects of international law. This Vienna Convention is perhaps one of the best, if not the best achievement of the International Law Commission which goes beyond a mere codification of then existing customary international law in trying and daring to include some innovative regimes, for instance, the regime on reservations, jus cogens and the validity and termination of international treaties. Mark Villiger, professeur titulaire at Zurich University, for a long time agent at the European Court of Human Rights and now Judge at that Court, is well-known as the author of an excellent handbook on the

practice of the European Convention on Human Rights1 and also of an extensive study on the relationship between customary international law and treaties2—both books now having been published in a second edition. He served for some time as Deputy-Registrar of the Section in the Court which I presided. Given the amount of work in the Court, I can only guess what sacrifice it may have been for him and his family to devote many evenings during the week in writing this commentary and doing the necessary research. Insofar, it is really to admire that such an excellent commentary is the outcome of the work of an international lawyer working in practice and not full-time at university.

One can ask the question what the public may expect from such a commentary. First of all, information on questions of interpretation of the di erent provisions of the Law of Treaties Convention and also on any possible future problems. Furthermore, precise answers for the solution of these problems as far as possible—and if not possible, reflections on alternatives. The reader will find that this commentary has achieved to give objective, reflective answers to the many questions he has found, also by carefully presenting the views of academic writings, the judgments of international and national courts, arbitrary awards, and State practice. It is obvious that Mark Villiger has carefully taken into account the judgments of the International Court of Justice, the European Court of Human Rights, and other international courts and tribunals in relation to treaty law. He has also given due account to the di erent types of international treaties and the influence which a di erentiation between the various types may have on their interpretation, such as, inter alia, the classification of human rights treaties and its consequences, e.g., for the regime of reservations. The language of the commentary is clear as are the answers to the di erent problems. What is really excellent is the classification of each provision into history, scope, background, interpretation, context, matters not dealt with, customary basis and, most challenging, a specific appreciation of the achievement of its wording.

The Vienna Convention on the Law of Treaties is part of the constantly moving set of rules of international law. It can therefore never be complete. From the very beginning legal analysts noted that there were deficiencies not only in the phrasing of some provisions but that a revision of some regimes of treaty law appeared to be necessary, such as the regime of res-

1Mark E. Villiger, Handbuch der Europäischen Menschenrechtskonvention (EMRK), 2nd ed. (1999).

2Id., Customary International Law and Treaties. A Study of Their Interactions and Interrelations with Special Consideration of the 1969 Vienna Convention on the Law of Treaties (1985); Id., Customary International Law and Treaties. A Manual on the Theory and Practice of the Interrelation of Sources, Fully Revised Second Edition (1997).