Customary Constraints on the Use of Force: Article 51 with an American Accent

Abstract

This Article, prepared for a symposium on ‘The Future of Restrictivist Theories on the Use of Force,’ examines the current trajectory of restrictivist scholarship in the United States. In contrast to their counterparts in continental Europe, American restrictivists tend to devote less energy to defending narrow constructions of the UN Charter. Instead, they generally focus on legal constraints outside the Charter’s text, including customary norms and general principles of law such as necessity, proportionality, deliberative rationality, and robust evidentiary burdens. The Article considers how these features of the American restrictivist tradition reflect distinctive characteristics of American legal culture, and it explores the tradition’s influence on debates over anticipatory self-defense and the use of force against non-state actors abroad. The Article concludes by examining how the American restrictivist tradition is beginning to shape the United States’ approach to the use of force in response to cyber attacks.

Keywords: use of force, self-defense, self-defence, restrictivism, UN Charter, Article 51, proportionality, necessity, cyber attacks