CYIL vol. 14 (2023)

CYIL 14 (2023) THE WORK OF THE INTERNATIONAL LAW COMMISSION AT THE BEGINNING … International Court of Justice. Second, they offer a consistent methodological approach when using subsidiary means for determining the existence and content of rules of international law. 23 2.5 Sea-level rise in relation to international law At the 2023 session of the Commission, the reconstituted Study Group had before it the Additional paper to the first issue paper, presented by Mr. Bogdan Aurescu and Ms, Nilüfer Oral, Co-Chairs of the Study Group. 24 The Addition paper deals with the important and often controversial issues of the impact of sea-level rise to the international law of the sea. The paper addressed the following issues and principles: meaning of “legal stability” in relation to sea-level rise, with a focus on baselines and maritime zones; immutability and intangibility of boundaries; fundamental change of circumstances (rebus sic stantibus); effects of the potential situation whereby overlapping areas of the exclusive economic zones of opposite coastal States, delimited by bilateral agreement, no longer overlap; effects of the situation whereby an agreed land boundary terminus ends up being located out at sea; principle that “the land dominates the sea”; historic waters, title and rights; equity; permanent sovereignty over natural resources; possible loss or gain of benefits by third States; nautical charts and their relationship to baselines, maritime boundaries and the safety of navigation; and relevance of other sources of law. The Study Group had an extensive exchange of views on the additional paper, with a focus on the preliminary observations prepared by the Co-Chairs. Concerning the principle of “legal stability”, members of the Study Group noted that this principle was embodied in the UN Convention on the Law of the Sea. It also contributed to the maintenance of international peace and security. The concepts of legal stability and respect for existing boundaries, that could be also applied to maritime boundaries, reflect customary international law. The Study Group also discussed the way in which the concept of legal stability is reflected in the context of the sea-level rise. As such ways, members considered (a) interpretation of the UN Convention on the Law of the Sea, (b) emergence of rules of customary international law, (c) subsequent agreements and subsequent practice, and (4) sui generis regimes. It seems that most members of the Study Group, as well as most States, prefer solutions that preserve the integrity of the UN Convention of the Law of the Sea. As one of the Co-chairs noted, the mandate of the Study Group was a mapping exercise of the legal questions raised by sea-level rise and its interrelated issues. 25 While this may certainly be a valuable work, one can ask the question whether this corresponds to the original mandate of the Commission, which is the progressive development of international law and its codification. The Study Group also held a discussion on the future programme of work on the topic. Members made various suggestions and outlined several options. With regard to the outcome of the Study Group’s work, various proposals were made, including a set of conclusions, an 23 See Report of the International Law Commission on the work of its seventy-fourth session, Official Records of the General Assembly, Seventy-eighth Session, Supplement No. 10 (A/78/10), p. 73. 24 See UN doc. A/CN.4/761 and Add. 1. 25 See Report of the International Law Commission on the work of its seventy-fourth session, Official Records of the General Assembly, Seventy-eighth Session, Supplement No. 10 (A/78/10), p. 94, para. 162.

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