José E. Alvarez, Herbert and Rose Rubin Professor of International Law, New York University School of Law; co-editor in chief, American Journal of International Law
"Michael Scharf’s Customary International Law in Times of Fundamental Change: Recognizing Grotian Moments is a masterful look at when and how radical developments accelerate the emergence of customary international law (described as "Grotian Moments"). Scharf’s careful development of the concept of Grotian Moments is to be applauded. His book closely analyses six scenarios from recent history in order to better identify both when such moments occur and when it seems like they might occur but nevertheless do not materialize. Why have some controversial legal pronouncements, such as joint criminal enterprise liability and the Tadić Appeals Chamber’s holding on the scope of ICTY’s provision regarding violations of the laws or customs of war, rapidly gained acceptance as customary international law? Why have other controversial legal pronouncements, such as the responsibility to protect doctrine and the recent expansion of the concept of anticipatory self-defense, not gained such rapid acceptance? Scharf newest work gives careful scrutiny to these legal issues and many others, and what results is a piece of scholarship from which international courts from this point forward can use to understand when customary international law develops and, just as importantly, why."
Judge Christine Van den Wyngaert, International Criminal Court
"This is a fascinating and thought-provoking book which deserves to be read by all those interested in international law and how it responds to new challenges. By focusing on six moments when customary international law may have undergone fundamental change in a short period of time, Michael Scharf has performed a real service to the international community."
Judge Christopher Greenwood, International Court of Justice
"In its totality, Customary International Law in Times of Fundamental Change: Recognizing Grotian Moments is a stimulating and challenging examination of how pivotal moments in history can precipitously affect the field of customary international law and international relations. At its best, this book has the potential to influence international law scholars who are deeply entrenched in their own views and spark interest in students of the law who have not yet embarked on their intellectual journeys."
George Washington International Law Review
"Professor Scharf examines the concept of the ‘Grotian Moment’, providing a critical yet thought-provoking analysis of the instances in which customary international law can, and indeed does, develop with surprising rapidity and limited state practice. Professor Scharf ’s contribution is widely set to leave its mark, as acknowledged by the authoritative list of names endorsing the book."
Jonathan Worboys, King's Law Journal
"… this is an excellent book. It is clearly and engagingly written (as anyone familiar with Scharf’s previous work would expect). The research underpinning it is similarly faultless. Moreover, it is short and to the point: its arguments are both concisely made and precisely targeted. This book is ultimately an extremely important addition to the literature. Its thesis is at the same time indisputable (in and of itself) and yet highly contestable both in terms of its framing and application to specific examples. Customary International Law in Times of Fundamental Change will undoubtedly spark important debate and further research on the process of expedited custom: a process that is controversial and potentially dangerous, but which - as Scharf ably demonstrates - undeniably occurs."
James A. Green, International and Comparative Law Quarterly