The armed attack requirement and customary international law: whose views count?

ABSTRACT Since the inception of the UN Charter, the specific parameters of an ‘armed attack’ triggering the right of states to use force in self-defence has been the subject of much academic discussion. Debate has intensified over the past two decades, with claims that state actions in the context of counter-terrorism have loosened the armed attack definition previously outlined by the International Court of Justice. This article explores how aspects of TWAIL insights on customary international law could be used to deepen the current debate on the armed attack requirement. Through analysis of opinio juris made outside the context of individual conflict events, it is argued that current debate favours perspectives of those more willing and able to use military force, with apparent geographical trends. Further, it is contended that greater consideration is needed of whose voices – both between and within states – are reflected within debates on the armed attack requirement.