COSIS Request for an Advisory Opinion: A Poisoned Apple for the ITLOS?

The request for an advisory opinion submitted by the Commission of Small Island States on Climate Change and International Law (COSIS) to the International Tribunal for the Law of the Sea (ITLOS) is part of a larger movement of strategic litigation in relation to climate change, essentially led by civil society. However, the seisin and the questions submitted revive debates on the Tribunal’s advisory jurisdiction. In the Sub-Regional Fisheries Commission Advisory Opinion, the ITLOS found that its advisory jurisdiction is based on the ITLOS Statute and on an external agreement with provisions for that purpose. However, the conditions for its exercise remain obscure. The COSIS request raises the thorny issue of the compatibility of the external agreement with the United Nations Convention on the Law of the Sea, in particular in light of Article 311. The authority of the Tribunal’s opinion depends largely on its care in addressing these difficulties head on.