The Function of Equity in International Law

Foreword by Christoph Schreuer

Oxford University Press 2021


This book provides a systematic and comprehensive study of the legal concept of equity as it operates in contemporary international law. A principle with a long pedigree, equity has been present in legal thought and in municipal legal systems since antiquity. Introduced in international legal decisions through claims commissions and arbitral tribunals, equity became progressively part and parcel of the international law mainstream. From international cultural heritage law to the law on climate change, from maritime boundary delimitations to decisions on security for costs in investment arbitration, the relevance of equity is more far-reaching than has previously been acknowledged. 

In contrast with earlier studies on the topic, this book is informed by a body of judicial and arbitral case law that has never been so substantial and varied. It also draws extensively on the prolific case law of investment tribunals, gaining insights from a valuable source that is typically overlooked in public international law scholarship. As the importance of international law increases, covering continuously new domains, the value of equity increases with it. It is this new equity in the international law of the 21st century that this book explores.


“highly original … – a must-read for anyone interested in the role of law and the state and future of the search for justice in the world!”

Andreas R. Ziegler, Professor, University of Lausanne Law School

“The author succeeds in keeping her audacious promise to explore the ‘turbulent depths’ spanned by equity, with a view to providing a new perspective. The good news is that the proposed new perspective corroborates the inner consistency of international law. The book offers authority galore and an enjoyable path through the cogs and wheels that move the international legal process.”

Attila M.Tanzi, Professor, University of Bologna, Associate Member, 3VB Chambers

“first-class systematic analysis … a must for all international adjudicators and an encouragement never to divorce the respect of hard-law provisions from justice in its application.”

Giorgio Sacerdoti, Emeritus Professor, International and European law, Bocconi University

“a must-read for all those interested in the development of international law and the role that equity has had and will continue to have in it.”

Rodrigo Polanco, WTI Senior Researcher and
Lecturer, Arbitration International

“the Author has succeeded in exposing with great clarity and precision a highly technical and controversial legal topic and the book will definitively constitute a relevant reference for both academics and practitioners”

Federica Cristani, Head of the Centre for International Law, Institute of International Relations Prague, Italian Yearbook of International Law Online

“In this important new study, Professor Titi has shone a searching spotlight on the equitable function of the international legal system, the significance of which has been much in need of contemporary re-evaluation.”

Campbell McLachlan QC, Professor, Victoria University of Wellington, Arthur Goodhart Visiting Professor of Legal Science, University of Cambridge 2021

“a reliable and practical guidebook for anyone interested in … international dispute resolution.”

Julien Chaisse, Professor, City University of Hong Kong, Journal of International Economic Law

“an important contribution to the doctrine and principle of equity in international law. … the author excels and succeeds in expounding the relevance of the principle of equity and of derived and related concepts in everyday international jurisprudence. … an excellent reference and solid ground to all who are interested and willing to further explore the underpinnings, the potential and future of equity in this period of global transition.”

Thomas Cottier, Emeritus Professor of Law, University of Bern, former Managing Director of the World Trade Institute, The Journal of World Investment & Trade