Tomas Heidar (Iceland) has been Judge of the International Tribunal for the Law of the Sea (ITLOS) since October 2014 and currently serves as Vice-President of the Tribunal (2020-2023). Earlier he was President of the ITLOS Chamber for Fisheries Disputes (2017-2020). He is 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, Tomas 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 lectures at the University of Iceland and many other universities and institutions around the world, including University College London, Queen Mary University of London, the British Institute of International and Comparative Law, the Yeosu Academy of the Law of the Sea and the IFLOS 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). He is also Conciliator and Arbitrator under Annexes V and VII to the United Nations Convention on the Law of the Sea.