In this article, I contribute to the debate between two philosophical traditions—the Kantian and the Aristotelian—on the requirements of criminal responsibility and the grounds for excuse by taking this debate to a new context: international criminal law. After laying out broadly Kantian and Aristotelian conceptions of criminal responsibility, I defend a quasi-Aristotelian conception, which affords a central role to moral development, and especially to the development of moral perception, for international criminal law. I show than an implication of this view is that persons who are substantially and non-culpably limited in their capacity for ordinary moral perception warrant an excuse for engaging in unlawful conduct. I identify a particular set of conditions that trigger this excuse, and then I systematically examine it as applied to the controversial case of former-child-soldier-turned leader of the Lord’s Resistance Army, Dominic Ongwen, who is currently at trial at the International Criminal Court
