NATO’s military intervention in response to the Federal Republic of Yugoslavia’s violation of human rights was illegal because it neither received the blessing of the Security Council nor was it justified under the rules of self-defense. This interdisciplinary research employs a rational choice approach to international law in order to understand the limits as well as the effects of international law during the Kosovo War in 1999. International law lacked any intrinsic importance within the utilitarian calculus of political decision-making during NATO’s intervention in 1999. After explaining a rational choice theory approach, this dissertation proceeds in the second chapter in order to outline the theoretical argument of jus ad bellum rules...