The Role of Opinio Juris in Customary International Law
Duke-Geneva Institute in Transnational Law
University of Geneva
July 12-13, 2013
Co-Sponsored by the American Society of International Law

University of Geneva Law Faculty Building
Uni Mail, 40 Boulevard du Pont d'Arve, CH-1211, Geneve 4

Friday, July 12


3:00 - 4:10 pm

Panel 1: Historical Origins of the Opinio Juris Requirement


Curtis Bradley, Duke Law School, The Chronological Paradox, State Preferences, and Opinio Juris
J. Patrick Kelly, Widener School of Law, Opinio Juris in Historical Context
Stephen Neff, Edinburgh Law School, Opinio Juris: Three Concepts Chasing a Label

Commentator: Marie Jacobsson, Swedish Ministry for Foreign Affairs; member of International Law Commission

4:10 - 4:20 pm

Coffee Break

4:20 - 5:30 pm

Panel 2: Does Customary International Law Need Opinio Juris?


Jörg Kammerhofer, University of Freiburg, Customary International Law Needs both Opinio and Usus
Brian Lepard, University of Nebraska College of Law, The Necessity of Opinio Juris in the Formation of Customary International Law
Maurice Mendelson QC, Blackstone Chambers, Does Customary International Law Require Opinio Juris?

Commentator: Michael Wood, 20 Essex Street; member of International Law Commission

5:30 - 6:30 pm


7:30 - 9:30 pm

Dinner for Participants



Saturday, July 13


9:00 - 9:30 am

Continental Breakfast

9:30 - 10:40 am

Panel 3: What Counts as Evidence of Opinio Juris?


Olufemi Elias, World Bank Administrative Tribunal & Chin Lim, University of Hong Kong, Proving Opinio Juris, and Customary International Law
Laurence Helfer, Duke Law School & Timothy Meyer, University of Georgia Law School, Codifying Immunity or Fighting for Accountability? International Custom and the Battle Over Foreign Official Immunity in the United Nations
Ingrid Wuerth, Vanderbilt Law School, National Court Decisions and Opinio Juris

Commentator: Sean Murphy, George Washington University School of Law; member of the International Law Commission

10:40 - 10:50 am

Coffee Break

10:50 am – 12:00 pm

Panel 4: Treaty Regimes and Opinio Juris


Joost Pauwelyn, The Graduate Institute, Treaty Regimes and Opinio Juris
Monica Hakimi, University of Michigan School of Law, Law and the Universal Human Rights Treaties
Richard Schmalbeck, Duke University School of Law, Opinio Juris in International Tax

Commentator: Georg Nolte, Humboldt University of Berlin; member of the International Law Commission

12:00 - 1:30 pm


1:30 – 2:40 pm

Panel 5: Relationship Between Opinio Juris and State Consent


Andrew Guzman, University of California, Berkeley School of Law, CIL and Non-Consensual Law
Niels Peterson, Max Planck Institute, Customary Law, Consent, and the Status Quo Paradox
John Tasioulas, University College London, Faculty of Laws, Custom and Consent

Commentator: Jan Wouters, Katholieke Universiteit Leuven 

2:40 - 2:50 pm

Coffee Break

2:50 - 4:00 pm

Panel 6: Is Opinio Juris a Unitary Phenomenon?


Noora Arajarvi, University of Central Lancashire, Cyprus, Changing Customary International Law and the Fluid Nature of Opinio Juris
Mitu Gulati, Duke Law School, How do Courts Find International Custom?
Emmanuel Voyiakis, London School of Economics, Rethinking the Normative Force of Customary International Law

Commentator: Catherine Kessedjian, University of Pantheon-Assas, Paris II