Contractualism in the Law of Treaties

Abstract

The Vienna Convention on the Law of Treaties, provides that “[a] treaty is void” if it has been “procured by the threat or use of force in violation of the principles embodied in the Charter of the United Nations” or if it “conflicts with a peremptory norm of general international law” – i.e., jus cogens. In the more than three decades since the Vienna Convention entered into force, however, neither of these provisions has been successfully invoked even once to challenge the validity of a treaty. In this Article, I undertake to explain why that is so – and why it should concern us. I argue that constraints on contractual freedom serve functions as critical to the law of treaties as they are to the law of contracts in domestic legal systems. But while such constraints won recognition in Vienna Convention, the procedures established by the Convention for their enforcement are radically contractualist: the International Court of Justice lacks jurisdiction over treaty invalidity claims unless the parties have consented to the Convention’s dispute resolution mechanism; moreover, third parties lack standing to challenge the validity of a treaty that was coerced or conflicts with peremptory norms, even though these rules implicate interests shared by the international community as a whole. This procedural framework saps the rules of much of their mandatory effect. Although a number of features of the international legal system make it unlikely in the foreseeable future that mandatory rules will serve all of the functions at the international level that they have come to serve in domestic law, I submit that some of their functions are of particular importance to international law. Accordingly, because post-hoc judicial invalidation of agreements – the primary means employed by domestic jurisdictions for enforcing mandatory rules – is ill suited to the decentralized structure of the international legal system, the international community should promote adherence to them through individual and collective action by states prior to the conclusion of treaties and through political, as well as judicial, processes and institutions.