The Effect of Article 4 of the Vienna Convention on the Law of Treaties 1969

Abstract

I. INTRODUCTION THE Vienna Convention on the Law of Treaties of 1969 (the "Vienna Convention") entered into force in 1980, and currently numbers approximately one quarter of the world's States among its parties. 1 The effect of the entry into force of the Convention is to make it possible to distinguish between rules which are authoritative only as a result of inclusion in the Convention itself ("pure" Convention rules) and those which exist independently as customary international law. In certain areas, particularly those importing new procedural provisions regarding dispute settlement, interpretation and modification of a treaty, the rules relating to the adoption of the text of a treaty and reservations, Vienna Convention rules do not have the status of customary international law. The effect of this lack of status when there is a dispute between parties to a convention not all of which are also parties to the Vienna Convention was thrown into some relief by the decision in the United Kingdom-France Continental Shelf arbitration. 2 Both the United Kingdom and France are parties to the 1958 Geneva Convention on the Continental Shelf. France acceded subject to a declaration the applicability of which to Article 6 of the Convention the United Kingdom did not accept. The arbitrators established that the United Kingdom had the right to object but the question of greatest interest for present purposes was the effect which that objection had upon the status of the reservation and, more importantly, the treaty relations between the two States. The French (significantly, not party to the Vienna Convention) argued that the mere objection of the United Kingdom to the reservation meant that the Convention as a whole did not come into force between the two States. This would have been the correct position under customary law before the Vienna Convention and is in accordance with the views expressed by the International Law Commission on the matter. The French argued that, because the UK had not expressly stated that treaty relations should result, the Conven