The Obligation not to Defeat the Object and Purpose of a Treaty in Light of Article 18 of the Vienna Convention on the Law of Treaties and New Developments

Abstract

Article 18 of the Vienna Convention on the Law of Treaties (VCLT) imposes an obligation on States not to defeat the object and purpose of a treaty prior to its entry into force when: (a) it has signed the treaty or; (b) it has expressed its consent to be bound by the treaty, pending the entry into force of the treaty and provided that such entry into force is not unduly delayed. It is the only rule of positive international law which imposes certain restraints on the conduct of States in the procedure of becoming parties to treaties. However, the contours of the provision are blurred. Within the current international legal discourse, there are several high-profile developments in the law of treaties which are capable of raising questions under Article 18 VCLT and which have not previously been critically addressed by scholars, practitioners or international courts or tribunals. Through a combination of doctrinal and qualitative empirical legal research, this thesis provides a comprehensive analysis of the content and status of the obligations of States in the process of becoming party to a treaty under Article 18 VCLT. In undertaking this analysis, the thesis addresses the following sub-questions: a) what is the legal origin of Article 18 VCLT; b) what is the notion of the object and purpose of a treaty; c) how does Article 18 VCLT apply in relation to the notion of the ‘object and purpose’ of a treaty; d) what is the threshold of ‘defeating’ the object and purpose of a treaty; e) what is the temporal scope of Article 18 VCLT; f) what is the legal nature of Article 18 VCLT and what are the consequences of a violation of this provision; g) how is Article 18 VCLT positioned within the framework of typologies of treaties; and h) is there a potential ‘reversal’ of Article 18 when a State has deposited its instrument of withdrawal from a treaty? To this end, the thesis addresses core issues of treaty practice and advances theoretical and practical ramifications of relevance for scholars, international judges, practitioners, and legal advisors of foreign ministries of States.