The Pacta Sunt Servanda Principle or the Limits of Interpretation: the Gabčíkovo-Nagymaros Case Revisited

Abstract

The Gabcikovo-Nagymaros case is particularly well-known for its clarification and specification of many questions of treaty law. Both Hungary and Slovakia presented numerous arguments that the 1977 Treaty concerning the construction and operation of the Gabcikovo-Nagymaros System of Locks had terminated or been suspended, or had rightfully been departed from. The International Court of Justice (ICJ, the Court), applying the Vienna Convention on the Law of Treaties (VCLT) on the basis of it largely codifying customary international law, responded by emphasizing the stability of treaty relations in light of the pacta sunt servanda principle in all respects. Despite the clarity seemingly surrounding the pacta sunt servanda principle and its role in international law, questions continue to emerge regarding the relationship between this ‘pillar’ of treaty law and the limits of treaty interpretation. Where does rightful interpretation in application of the pacta sunt servanda principle end? Where does an undue revision of the treaty — not within the confines of the pacta sunt servanda principle — start? These questions were at the heart of the Court’s discussion of the pacta sunt servanda principle when drawing the line between interpretation and approximate application of the 1977 Treaty. The Court’s majority opinion in the Gabcikovo-Nagymaros case and a number of opinions and declarations appended to the Judgment therefore prove particularly valuable to clarify these questions. Hence, on the basis thereof, the two techniques of treaty interpretation stretching the limits of the pacta sunt servanda principle are discussed in the following: firstly, the principle of approximate application, rejected by the Court; and secondly, the technique of evolutionary interpretation, as applied by the Court itself. On the basis thereof, it is concluded that the upholding of the principle of pacta sunt servanda in the case at hand indeed reaffirmed the stability of treaty relations. At the same time, however, it did not and does not necessarily respond to the political reality on the ground.