Exceptio Inadimplenti Non Est Adimplendum at the Intersection of Treaty Law and Law of International Responsibility
The principle commonly referred to as exceptio inadimplenti non est adimplendum or exceptio inadimpleti contractus provides that in international law, the performance of an obligation may be withheld if the other party has itself failed to perform the same or a related obligation. Being based on reciprocity, it aims, therefore, to establish a fair balance between the parties. Article 60 of the 1969 Vienna Convention on the Law of Treaties reflects the foundations of exceptio inadimplenti non est adimplendum. Paragraph one states that “A material breach of a treaty by one of the parties entitles the other to invoke the breach as a ground for terminating the treaty or suspending its operation in whole or in part.” However, by referring only to material breaches, this article does not make general reference to the traditional and classical version of the principle. Besides, Article 73 of the 1969 Convention, by providing that “the provisions of the Convention shall not prejudge any question that may arise in regard to a treaty from the international responsibility of a State,” explicitly stipulates that in case of treaty violations, international responsibility rules would also apply. The question then arises whether exceptio inadimplenti non est adimplendum could be considered as a countermeasure under the law of State responsibility. This article focuses on whether exceptio has its roots and foundations in the law of treaties or in the law of international responsibility.
Andlaşmalar Hukuku ve Uluslararası Sorumluluk Hukukunun Kesişim Noktasında Exceptio Inadimplenti Non Est Adimplendum
Uluslararası hukukta exceptio inadimplenti non est adimplendum veya exceptio inadimpleti contractus olarak adlandırılan ilke bir uluslararası hukuk kişisinin bir uluslararası yükümlülüğünü yerine getirmediği durumlarda, yükümlülüğün muhatabı olan diğer uluslararası hukuk kişisinin aynı veya benzer bir yükümlülüğünü yerine getirmeyebileceğini öngörmekte ve karşılıklılık üzerine kurulu bir anlayışla, taraflar arasında âdil bir denge kurmayı hedeflemektedir. 1969 Viyana Andlaşmalar Hukuku Sözleşmesi’nin 60. maddesi bir uluslararası andlaşmanın, âkit taraflardan biri tarafından ihlâl edilmesi durumunda, diğer âkit tarafın andlaşmayı sona erdirebileceğini veya tamamen veya kısmen yürürlüğünü askıya alabileceğini düzenleyerek exceptio inadimplenti non est adimplendum ilkesinin temelindeki anlayışı benimsiyor olsa da ihlâlin “esaslı” olması gerektiğini hükme bağlayarak ilkeye genel bir atıf yapmamaktadır. Bunun yanı sıra, 1969 Sözleşmesi’nin 73. maddesi genel uluslararası sorumluluk hukuku kurallarına atıfta bulunmakta ve sözleşme hükümlerinin, devletlerin uluslararası sorumluluğa ilişkin kurallarına halel getirmeyeceğini hükme bağlayarak bir uluslararası andlaşmanın ihlâli durumunda uluslararası sorumluluk hukuku kurallarının da devreye girebileceğini açıkça düzenlemektedir. İşte bu noktada, exceptio inadimplenti non est adimplendum ilkesinin uluslararası sorumluluk hukuku altında bir karşı önlem telâkki edilip edilemeyeceği sorusu gündeme gelmektedir. Elinizdeki çalışma, ilkenin temellerini andlaşmalar hukukundan mı yoksa uluslararası sorumluluk hukukundan mı aldığı, başka bir ifade ile, andlaşmalar hukuku ve sorumluluk hukuku arasında exceptio ilkesi bağlamında bulunan ilişkinin bir rekabet ilişkisi mi yoksa bir tamamlayıcılık ilişkisi mi olduğu sorusuna odaklanmaktadır.
The principle commonly referred to as exceptio inadimplenti non est adimplendum or exceptio inadimpleti contractus provides that in international law, the performance of an obligation may be withheld if the other party has itself failed to perform the same or a related obligation. Being based on reciprocity, it aims, therefore, at establishing a fair balance between the parties.
Article 60 of the 1969 Vienna Convention on the Law of Treaties reflects the foundations of exceptio inadimplenti non est adimplendum. Paragraph one states, “A material breach of a treaty by one of the parties entitles the other to invoke the breach as a ground for terminating the treaty or suspending its operation in whole or in part.” However, by referring only to “material” breaches, this article does not make a general reference to the traditional and classical version of the principle. Besides, Article 73 of the 1969 Convention, by providing that “the provisions of the Convention shall not prejudge any question that may arise in regard to a treaty from the international responsibility of a State,” explicitly stipulates that in case of treaty violations international responsibility rules would also apply. The question then arises whether exceptio inadimplenti non est adimplendum could be considered as a countermeasure under the law of State responsibility. This article focuses on whether this principle has its roots and foundations in the law of treaties or in the law of international responsibility.
The article analyses the principle of inadimplenti non est adimplendum firstly in the context of the law of treaties and discusses whether the principle is regulated by Article 60 of the 1969 Vienna Convention on the Law of Treaties. Indeed, although there is no doubt that Article 60 is based on reciprocity and reflects a certain understanding of exceptio inadimplenti non est adimplendum, whether it provides the classical version of this principle is controversial.
Paragraph 1 of Article 60 does not adopt a general reciprocity conception and appears to be a narrow version of exceptio inadimplenti non est adimplendum that can be invoked in cases of all breaches, whether material or not. Besides, despite the fact that there are no procedural requirements for the invocation of exceptio, Article 60 of the 1969 Convention provides procedural rules that States should respect when they invoke the right that this article confers upon them regarding the termination and the suspension of treaties. Finally, Article 60 stipulates that a material breach of a treaty by one of the parties would entitle the other party to invoke the breach as a ground for terminating the treaty or suspending its operation “in whole or in part.” In contrast, according to the classical interpretation of exceptio, the injured State has the right not to perform “the same” or “a related obligation” that has been violated by the other State.
All these differences lead some international legal scholars to argue that Article 60 of the 1969 Convention does not regulate the principle of exceptio and that exceptio has its roots in the law of international responsibility. In this context, exceptio inadimplenti non est adimplendum is analyzed, secondly, under the law of State responsibility focusing on its differences from countermeasures.
Indeed, the objective of the Vienna Convention on the Law of Treaties is to regulate the relationship between the parties to a treaty and not the legal consequences of internationally wrongful acts committed in this field, such as the right to reparation arising from the violation of contractual obligations. Besides, although Article 60 of this Convention applies when there is a “material” breach of a treaty by one of the parties, countermeasures can be taken against all violations of international obligations, conventional or customary, as far as they respect the principle of proportionality. Moreover, Article 60 confers on injured States the right to terminate or suspend the concerned treaties only, whereas countermeasures can appear as violations of all international law rules, except those provided for in Article 50 of the 2001 Draft Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA). Finally, the procedural requirements provided by Article 60 of the 1969 Convention are stricter than the procedural rules that States should respect while adopting countermeasures according to Articles 49‒53 of the ARSIWA.
Despite all these differences, the confusion between exceptio, Article 60 of the 1969 Convention, and countermeasures continues to exist, and this confusion is not cleared up by international jurisprudence. This paper also reviews the concerned jurisprudence and analyzes the decisions concerning the Diversion of Water from the Meuse, the ICAO Council, the Air Service Agreement of 27 March 1946 between the United States of America and France, the Rainbow Warrior case, the Gabčikovo-Nagymaros Project, and the Application of the Interim Accord of 13 September 1995.
All these considerations lead to the conclusion that exceptio inadimplenti non est adimplendum is a principle whose presence is felt in all international law institutions, based on reciprocity. However, no legal text regulates the principle in its traditional and classical form. Article 60 of the 1969 Convention seems to be a narrow version of exceptio, applicable in the law of treaties, whereas countermeasures that carry the traces of exceptio appear to be a metamorphosed form of this institution.
