International law is constantly navigating the tension between preserving the status quo and adapting to new exigencies. But when and how do such adaptation processes give way to a more profound transformation, if not a crisis of international law? To address the question of how attacks on the international legal order are changing the value orientation of international law, this book brings together scholars of international law and international relations. By combining theoretical and methodological analyses with individual case studies, this book offers readers conceptualizations and tools to systematically examine value change and explore the drivers and mechanisms of these processes. These case studies scrutinize value change in the foundational norms of the post-1945 order and in norms representing the rise of the international legal order post-1990. They cover diverse issues: the prohibition of torture, the protection of women's rights, the prohibition of the use of force, the nonproliferation of nuclear weapons, sustainability norms, and accountability for core international crimes. The challenges to each norm, the reactions by norm defenders, and the fate of each norm are also studied. Combined, the analyses show that while a few norms have remained surprisingly robust, several are changing, either in substance or in legal or social validity. The book concludes by integrating the conceptual and empirical insights from this interdisciplinary exchange to assess and explain the ambiguous nature of value change in international law beyond the extremes of mere progress or decline.