The End of the United Nations? The Demise of Collective Security and Its Implications for International Law

This is the author accepted manuscript. The final version is available from Brill via the link in this recordA dynamic shift in global power balance and the rapid pace of technological advances are likely to pose an existential threat to the United Nations (‘UN’) and its collective security system. The political impasse at the Security Council has undermined its ability to address international security crises in recent years. Proceeding with the assumption that the UN collective security system ceases to perform its function, this article provides a thought experiment (Gedankenexperiment) on how international law might operate and evolve in the absence of collective security enforcement. The primary focus of this inquiry is to what extent the fundamental structure of international law might revert to the pre-Charter era and how the modern development of international law achieved under the UN Charter might survive and set a course for normative restructuring. This article tests the hypothesis that the receding institutional capacity to contain destabilising behaviour will have a normative impact on the existing rules of international law, insofar as their modern development has depended upon the institutional framework for collective security. It does so by examining the normative impact in the following three areas of international law: (1) jus ad bellum; (2) the legal authority of regional institutions for collective security; and (3) restrictions on military support to a belligerent involved in international armed conflict under the law of neutrality. It finds that the legal implications of the demise of collective security are likely to be limited, with a gradual shift in State practice and an associated change in opinio juris as States interact with specific instances of security threats