Annual Grotius Lecture 2025: The Advisory Opinion of ITLOS on Climate Change: A Landmark Decision

Event Details

On 21 May 2024, the International Tribunal for the Law of the Sea (ITLOS) unanimously rendered the Advisory Opinion on the Request submitted by the Commission of Small Island States on Climate Change and International Law. The Advisory Opinion, which has been referred to as a "landmark decision", has brought climate change into the realm of the Law of the Sea Convention and activated its provisions, in particular in Part XII, with regard to anthropogenic greenhouse gas emissions. In his lecture, President Heidar will shed light on the distinctive nature of the Advisory Opinion by identifying some key points.

The lecture will be followed by a Q&A with the audience. 

Please note that this is an in-person-only event held at the BIICL office in London; however, the recording will be made available here after the event.

Book your place using the form below

Event convened by Kristin Hausler, Dorset Senior Research Fellow in Public International Law and Director, Centre for International Law, BIICL.

Join the conversation on BlueSky #GrotiusLecture2025

Biography

Judge Tomas Heidar is President of the International Tribunal for the Law of the Sea (ITLOS). He has been Judge of the Tribunal since 2014 and was President of the ITLOS Chamber for Fisheries Disputes 2017-2020 and Vice-President of the Tribunal 2020-2023. He was a Member of the ITLOS Special Chamber in the Dispute concerning delimitation of the maritime boundary between Mauritius and Maldives in the Indian Ocean.

From 1996-2014, Judge Heidar served as Legal Adviser of the Ministry for Foreign Affairs of Iceland, attaining the rank of Ambassador. As such he was responsible for all matters of public international law and represented Iceland regularly at meetings on ocean affairs and the law of the sea at the United Nations and in other international fora.

Judge Heidar is also Director of the Law of the Sea Institute of Iceland and Co-director and lecturer of the Rhodes Academy of Oceans Law and Policy. He has lectured at the University of Iceland and many other universities and institutions around the world, including the University of Oxford, Queen Mary University of London, University College London, the British Institute of International and Comparative Law, Leiden University, the University of Virginia, the IFLOS Summer Academy, the Yeosu Academy of the Law of the Sea and the Kadir Has International Law of the Sea Summer Academy. He has taught law of the sea at the United Nations Regional Course in International Law in Ethiopia.

Judge Heidar has published numerous books and articles on ocean affairs and the law of the sea, most recently New Knowledge and Changing Circumstances in the Law of the Sea (ed., Brill Nijhoff, 2020), "The Contribution of the International Tribunal for the Law of the Sea to the Protection of the Marine Environment" in the Korean Journal of International and Comparative Law (2021) and International Fisheries Law: Persistent and Emerging Challenges (co-ed., Routledge, 2025). He is also Conciliator and Arbitrator under Annexes V and VII to the United Nations Convention on the Law of the Sea.