New CERL-OUP volume explores navigating rivalries that take place below the threshold of armed conflict

The Center for Ethics and the Rule of Law (CERL) is pleased to announce the publication of its thirteenth edited volume with Oxford University Press, Hybrid Threats and Grey Zone Conflict: The Challenge to Liberal Democracies.

“This book brings together an outstanding cast of authors from academia, legal practice and beyond who have done an amazing job of addressing what is a complex and at times controversial subject,” said volume co-editor and author Aurel Sari.

A total of 39 experts contributed to the 28-chapter volume, which considers three main questions. First, what are the strengths and shortcomings of the existing rules and institutions of international law in responding to hybrid threats and grey zone conflicts? Second, what role does the law play as an instrument, domain and object of geopolitical contestation in the contemporary strategic environment? Third, how should liberal democracies respond to the challenges posed by hybrid and grey zone competition in a way that does not undermine the very values they seek to uphold?

“Although many of these legal, policy and ethical dilemmas have been addressed before, the aim of this volume is to do so systematically and in greater depth so as to contribute to a better understanding of the field and to efforts to develop more effective responses to counter the adverse effects of hybrid and grey zone conflict on liberal democracies and on the international rule of law,” said Sari.

The volume was edited by Mitt Regan, McDevitt Professor of Jurisprudence and Co-Director of the Center on National Security at Georgetown Law Center, and Senior Fellow at the Stockdale Center for Ethical Leadership at the U.S. Naval Academy, and Aurel Sari, an Associate Professor of Public International Law at the University of Exeter and a Fellow of Supreme Headquarters Allied Powers Europe. 

“This extraordinary collection of expert essays provides a thorough survey of the complexities of grey zone conflict along with a number of the techniques of hybridized warfare,” said CERL Faculty Director Claire Finkelstein. “Mitt Regan and Aurel Sari have done a great service by bringing these various chapters together in one place and by addressing some of the most difficult legal and ethical questions that arise in the context of grey zone operations. We are delighted to add this volume to the CERL-OUP series.”

The volume’s 28 chapters are organized into four distinct sections: 

  • The first, entitled What are Hybrid Threats and Grey Zone Conflict?, brings together contributions that address the conceptual foundations of the subject and explore the meaning, features and utility of the hybrid threat and grey zone conflict notions, including their legal aspects, the divide between war and peace and the principle of non-intervention.
  • The second, Arenas of Hybrid and Grey Zone Competition, is devoted to some of the main functional and thematic domains in which hybrid and grey zone competition takes place, including the information domain, cyberspace, new technologies, the maritime environment and outer space.
  • The third, Instruments, Tactics, and Methods in the Grey Zone, takes a closer look at the means and methods of hybrid and grey zone competition, with chapters decoding key instruments and actors, the logic of coercion, the role of lying, non-State actors and the weaponization of dissent.
  • The fourth, Countering Hybrid and Grey Zone Threats: How Can Liberal Democracies Respond,  focuses on the ethical, legal and practical considerations that liberal democracies face in their efforts to counter hybrid and grey zone threats, featuring chapters on the need for democracies to stand up for their core values, the range of ethically permissible responses and contributions on legal resilience by practitioners from Israel, Finland and NATO.

Click here for the full table of contents and a complete list of contributors.

Mailing List


Submissions to The Rule of Law Post. Please refer to CERL’s submission guidelines for additional details on the blog post format. Should your submission be accepted, we ask that you please complete the Agreement to Transfer Copyright.

Please upload text in one document under 6 mb. Preferred format as a simple text file (.txt).

Share New CERL-OUP volume explores navigating rivalries that take place below the threshold of armed conflict on:

New CERL-OUP volume explores navigating rivalries that take place below the threshold of armed conflict