Uploaded March 2025 | Updated September 2026, 3 weeks ago

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Customary international law is a crucial source of international law because once it is identified, it is binding on all States. But determining whether an applicable rule of customary international law exists is not always simple or straightforward.

Moderated by the School’s Professor of International Law Philippa Webb, Sir Michael Wood and Dr Sender, the authors of Identification of Customary International Law, will share guidance and insights on how to determine the existence and content of rules of customary international law.

They will reflect on the methodology and examine practical questions concerning the process and evidence involved. Professors Çalı and Akande will serve as discussants. There will be plenty of time for questions, including on the challenges of providing advice in a shifting legal landscape.

The event is jointly hosted by the Blavatnik School of Government, the Bonavero Institute and the Faculty of Law, University of Oxford.

Blavatnik School of Government,
University of Oxford
bsg.ox.ac.uk