UCL Faculty of Laws


Identifying customary international law

19 October 2016, 6:00 pm–7:00 pm

ILA Mendelson

Event Information

Open to



International Law Association


UCL Gavin de Beer Lecture Theatre, Anatomy Building, Gower Street, WC1E 6BT


Identifying Customary International Law:
From the International Law Association’s Principles of 2000 to the International Law Commission’s 2016 draft

by Professor Maurice Mendelson QC
Blackstone Chambers

Chaired by Professor Roger O’Keefe (UCL Laws)

This lecture is accredited with 1 CPD hour.

About the lecture

In 2000 the International Law Association adopted the London Principles on the Formation of Customary International Law and commended it to governments, international organisations etc. The International Law Commission of the United Nations subsequently took up the subject with a view to possible codification, and in 2016 adopted a draft, on first reading, which has been transmitted to governments for their comments. The speaker, who chaired the International Committee which drafted the ILA Principles, will consider the challenges of codification and make some brief comparisons between the two documents.

About the speaker

Maurice Mendelson is a barrister (Queen’s Counsel) at Blackstone Chambers, London, specializing in public international law. He has been in practice at the English and international Bar since 1971; from 1968 to 2001 he also held academic posts at the Universities of Oxford and London, most recently the Chair of International Law at University College London, of which he is now Emeritus Professor of International Law. He has represented and advised numerous governments, inter-governmental and non-governmental organizations, multinational and other corporations, and individuals, covering most branches of international law.  He has also sat as an arbitrator and given expert evidence before foreign courts and international tribunals.  His special interests include customary international law: he was the Chairman of the ILA International Committee that produced the 2000 London Principles on the formation of Customary (General) International Law, and also (inter alia) gave a course of lectures at The Hague Academy on the subject, published as “The Formation of Customary International Law”, 272 Collected Courses (1998), 155-410.

His full list of publications can be found at