Customary International Law Today: Symposium on
The Theory, Practice and Interpretation of Customary International Law
(Cambridge University Press, 2022)
INTRODUCTORY BLOG
What is the Point of The Theory, Practice, and Interpretation of Customary International Law?
by Jörg Kammerhofer & Panos Merkouris
Published on 15 November 2022
In early 2018, we started planning a conference on the theoretical aspects of customary international law (CIL) as the first instalment of the European Conference Series on the Theory and Philosophy of International Law. This conference, co-organised by Panos Merkouris’ ERC-funded research project TRICI-Law and by the European Society of International Law’s Interest Group on International Legal Theory and Philosophy (IGILTP), then chaired by Jörg Kammerhofer, was held in May 2019 at the University of Groningen. In early 2022, we published an edited volume with Cambridge University Press whose chapters are based on the papers presented at the conference, edited by us with Noora Arajärvi; Nina Mileva as assistant editors. It is available open access on Cambridge Core.
Published on 16 November 2022
Treaties and Determination of Customary International Law by Courts and Tribunals: Are There Limits to the Use of Methodological Shortcuts?
by Xuexia Liao
The significance of treaties for the identification of customary international law is well recognised and the modes of interaction between treaty and customary international law clearly formulated, notably in the 1986 Nicaragua case and in Conclusion 11 of the International Law Commission’s (ILC) Conclusions on Identification of Customary International Law. Nevertheless, a recurring theme that fully reveals the difficulties of ‘understand[ing] customary international law in all its complexity’ (Jörg Kammerhofer & Panos Merkouris in the introductory blog post) is that, in practice, international courts and tribunals exclusively or primarily rely on the texts of the treaties not just as a starting point of assessing the customary process, but as a methodological shortcut in the identification procedure.
Published on 18 November 2022
Conceptual and Practical Problems in the Change or Termination of Rules of Customary International Law
by Alvin Yap
Once in existence, how do rules of customary international law change or terminate? This topic was intentionally not dealt with by the International Law Commission (ILC) in its Draft conclusions on identification of customary international law (see Commentary (5) to Draft Conclusion 1). Yet, it is a matter of significant academic and practical interest. This post raises a few general points concerning how rules of customary international law could change or terminate.
Published on 21 November 2022
Between theory, practice, and ‘interpretation’ of customary international law
by Michael Wood and Omri Sender
Customary international law remains a principal source of international law, and it comes therefore as no surprise that it continues to capture the attention—and imagination—of scholars and practitioners alike. The recently published volume entitled The Theory, Practice, and Interpretation of Customary International Law contains some thoughtful essays on questions both old and new, seeking to add to a scholarly discussion on customary international law that spans centuries of legal thought. This longstanding intellectual effort, as Kadens and Young have shown elsewhere, has grappled with theoretical difficulties that indeed ‘have been around for more than half a millennium.’ It has also demonstrated, they observe, that ‘[t]he prospects for international custom must be assessed in light of actual experience, not just theory.’
Published on 23 November 2022
Methodologies for the identification of customary international law from the perspective of a government legal advisor
by Kristi How
In this short blog post, I aim to provide my views on the methodologies for the identification of customary international law (CIL) from the perspective of my personal experience as a government legal advisor. However, as stated by Judge Tanaka in his dissenting opinion in North Sea Continental Shelf, determining the existence or lack of State practice and opinio juris is ‘a delicate and difficult matter’. Given the necessarily imprecise exercise that one must undertake to assess the existence of general and consistent practice that is accepted as law, I cannot claim to represent all government legal advisors, or my own government for that matter, on this issue or cover the plurality of perspectives in the identification of CIL.
Symposium Concluding Blog
Published on 25 November 2022
The Theory and Practice of Customary International Law: What’s Interpretation Got to Do with It?
by Nina Mileva
In the introduction to this symposium, Kammerhofer and Merkouris end their post by reminding us that reports of the death of the conceptual and theoretical problems of customary international law (CIL) have been greatly exaggerated. Indeed, having read the insightful posts by Xuexia Liao, Alvin Yap, Michael Wood and Omri Sender, and Kristi How, I cannot help but emphatically agree.