The Lawfulness of Unilateral Sanctions in the Wake of a US–China “Sanctions War”

Abstract Despite what many saw as a détente in US–China relations as presidents Biden and Xi met at the G20 Summit in November 2022, both countries have continued to develop and deploy sanctions against one another. Among the most recent actions by the US is the continued use of export controls, particularly to limit China’s access to advanced computing chips. Meanwhile, China has continued to use sanctions to target US firms, recently in the form of a national security investigation into US chip maker, Micron, and “countermeasures” against major US arms manufacturers such as Raytheon and Lockheed Martin. This Article examines the range of economic sanctions that the US and China have and could deploy against one another, the lawfulness of these measures, and the likely effects of these sanctions for the future of international sanctions law. Although unilaterally imposed economic sanctions remain a deeply contested area of international law, an unintended consequence of the increasing use of sanctions by the world’s two largest economies will be to lend legitimacy and legality to their use. Although the economic costs of a US–China sanctions war would be staggering, such a war would only further entrench unilateral sanctions as a fundamental tool of national security and foreign relations. This Article describes how international law is likely to develop as a consequence of the proliferation of sanctions, arguing that, far from undermining their lawfulness, increased state practice will support a customary norm of unilaterally imposed sanctions.