Crises have long been central to accounts of change in International Law, but the factors determining why some crises elicit changes in international legal discourse while others do not remain insufficiently examined. This dissertation seeks to address this gap by exploring the question: Which crises are more likely to trigger changes in international legal discourse, and why? In this work, I shall examine the relationship between “crisis” and International Law, challenging the notion that International Law is simply a “discipline of crisis”, but rather a discipline of “particular crises”. I shall argue that perception plays a crucial role in framing the relevance of crises within international legal discourse. More precisely, integrating perspectives from philosophy, cognitive psychology, and social psychology, this study challenges conventional accounts of crisis-driven change in International Law. Building on Nassim Nicholas Taleb’s Black Swan Theory, it argues that unforeseen, high- impact crises – conceptualized here as Black Swans in International Law – are particularly likely to drive significant shifts in legal discourse. However, the analysis goes beyond this premise to examine the conditions under which such events influence international legal discourse, focusing on why similarly unpredictable and high-impact crises may fail to produce comparable discursive changes. This dissertation examines key human biases – including Western bias, representativeness and availability heuristics, ingroup/outgroup dynamics, media framing, hegemonic influence, and the notion of moral proximity – that determine how crises are perceived and prioritized within international legal discourse. By conducting a qualitative comparative analysis of the Kosovo War and the First Liberian Civil War, this dissertation analyses how (mis)perceptions shape the prominence of particular crises in legal debates, sidelining others of comparable importance. The findings reveal that crises are not inherently equal in their capacity to shape international legal discourse; instead, cognitive shortcuts and human biases often determine their perceived importance.