Waging War against Non-State Actors: The Contemporary Debate on the Prohibition of Force

Recent events have triggered scholarship arguing that international law should embrace the widespread state practice of using force against violent non-state actors such as terrorists. The evolution of state practice since 9/11 suggests an alternate interpretation of Article 2(4) and Article 51 of the UN charter, per treaty mechanisms. Specifically, academics and government officials have argued that the threat posed by terrorism necessitates lowering the state responsibility threshold. Doing so would make states hosting terrorists liable for violence undertaken from within their territory, giving aggrieved nations a license to intervene militarily. This essay argues that the traditional legal understanding of Article 2(4) and 51, which prohibit the use of force except in self-defence and then only against state actors, should be upheld, as war is not an effective means of eliminating non-state actor violence. Rather, nations need to address non-state actor violence by focusing on economic and social measures which foster development in failing States, as addressing civilian grievances is the most effective way to combat and deter terrorism.