In response to some of the most protracted and brutal conflicts of the last twenty years, the United Nations has created several ad hoc criminal tribunals tasked with bringing the perpetrators of war crimes, crimes against humanity, and crimes of genocide to justice. This book analyses the jurisprudence of these ad hoc tribunals, comprising the International Criminal Tribunal for the Former Yugoslavia, the International Criminal Tribunal for Rwanda, and the Special Court for Sierra Leone. Their decisions have been the subject of considerable discussion with regard to their approach and contributions to international criminal law. However, their contributions to international humanitarian law, through its interpretation and application, have been largely overlooked. This is unfortunate given that the ad hoc tribunals, through the prism of international criminal law, have taken the view that to determine whether conduct amounts to a war crime requires a detailed analysis of international humanitarian law. The Development of International Humanitarian Law by the International Criminal Tribunals critically evaluates the jurisprudence of the ad hoc tribunals towards international humanitarian law and identifies how this jurisprudence has in turn influenced the progressive development of the law. It discusses the pronouncements of the ad hoc tribunals on both treaty and customary norms of international humanitarian law, maintaining particular focus on the interpretation of those norms to further understand the detail of the law invoked. Equally, the book critiques instances in which the ad hoc tribunals have declined to deal with some of the important international humanitarian law issues that have arisen before them.