The focus of this edited volume is the often-overlooked importance of secondary rules of international law. Secondary rules of international law-such as attribution, causality, and the standard and burden of proof-have often been neglected in scholarly literature and have seen fragmented application in international legal practice. Yet the systemic nature of international law entails that coherent and consistent application of such rules is a key element in reinforcing the legitimacy of decisions of international courts and tribunals. Accelerated development of international law and international litigation, coupled with the fragmented nature of the adjudicatory terrain calls for theoretical scrutiny and systemic analysis of the developments in the judicial treatment of secondary rules.

This publication makes three important contributions to the study of secondary rules. First, it offers a comprehensive, expert doctrinal analysis of how standard of review, causation, evidentiary rules, and attribution operate in the case law of international courts or tribunals in fields spanning human rights, trade, investment, and humanitarian law. Second, it comparatively evaluates the divergent layers of meanings and normative expectations attached to secondary rules in international law scholarship as well as in the judicial practice of international courts and tribunals. Finally, the book investigates the role that secondary rules play in the development of the primary rules in international law and for the legitimacy of the decisions of international courts and tribunals.

Earlier scholarly works have not problematized the role of secondary rules of international law in adjudication thoroughly. Secondary Rules of Primary Importance in International Law seeks to fill this gap by emphasizing the consequential nature of these secondary rules and argues that the outcome of litigation is fundamentally shaped by the exact standard of proof, standard of review, or attribution basis that is chosen by adjudicators. As such, the book offers an important resource for the study and practice of international law against the backdrop of the wide-ranging and fragmented nature of international adjudication.

About the Author:
Gábor Kajtár, Associate Professor, ELTE Law School, Basak Çali, Professor of International Law, Hertie School, Marko Milanovic, Professor of Public International Law, University of Nottingham

Gábor Kajtár is Associate Professor in International Law at ELTE Law School Budapest. He holds a Law degree, an MA in Political Sciences, and an LL.M. degree from the University of Cambridge (2007). His Ph.D. dissertation concerned the self-defence against non-state actors and was awarded the Pro Dissertatione Iuridica Excellentissima Award, given to the best legal PhD dissertation in 2013-2014 by the Hungarian Academy of Sciences. Dr. Kajtár was a Visiting Researcher at Harvard Law School in the academic year 2015/2016, a Leibniz Fellow at the Max Planck Institute in Heidelberg in 2017, and a Visiting Fellow at the Lauterpacht Centre in 2019. Dr. Kajtár has been the coach of ELTE Jessup Team since 2009 and the ELTE Telders Team since 2016. In 2019 his team won the Jessup World Championship Final in Washington DC.

Basak Çali is Professor of International Law at the Hertie School and Co-Director of the School's Centre for Fundamental Rights. She is an expert in international law and institutions, international human rights law, and policy. She has authored publications on theories of international law, the relationship between international law and domestic law, standards of review in international law, interpretation of human rights law, legitimacy of human rights courts, and implementation of human rights judgments. She is the Chair of the European Implementation Network and a Fellow of the Human Rights Centre of the University of Essex. She has acted as a Council of Europe expert on the European Convention on Human Rights since 2002. She has extensive experience in training members of the judiciary and lawyers across Europe in the field of human rights law. She received her PhD in International Law from the University of Essex in 2003.

Marko Milanovic is Professor of Public International Law at the University of Nottingham School of Law and Co-Director of its Human Rights Law Centre. He is co-editor of EJIL: Talk!, the blog of the European Journal of International Law, as well as a member of the EJIL's Editorial Board. Professor Milanovic was formerly Vice-President and member of the Executive Board of the European Society of International Law. He held visiting professorships at Michigan Law School, Columbia Law School, Deakin Law School, the University of the Philippines College of Law, and the Geneva Academy of International Humanitarian Law and Human Rights.