Written by Yunjun Li

The uniqueness of the continental shelf beyond 200 nautical miles (NM) creates its own complexity. According to the 1982 United Nations Convention on the Law of the Sea (LOSC),[1] the continental shelf beyond 200 NM is a legal concept combined with geological and geomorphological elements. Compared with other maritime areas prescribed in the LOSC, the extent of which can be easily ascertained by a fixed distance from a baseline,[2] the outer limit of the continental shelf beyond 200 NM needs to be determined through a set of complicated scientific and technical formulae and constraints provided in Article 76(2)-(7).

Considering the scientific complexity of applying Article 76(2)-(7), it was deemed necessary to establish a technical organ capable of reviewing the outer limit lines claimed by States to ensure the appropriate application of Article 76. The result was the establishment of the Commission on the Limits of the Continental Shelf (CLCS), the main purpose of which is to provide certainty to the technical determination of the physical limits of the continental shelf beyond 200 NM. The CLCS has two main functions: the first is to evaluate whether a coastal state has conformed to Article 76 when delineating the outer limits of the continental shelf beyond 200 NM and to issue recommendations on this; the second is to provide technical advice to states when requested.[3] In order to facilitate the discharge of these functions, the Rules of Procedure of the Commission on the Limits of the Continental Shelf (Rules of Procedure)[4] has been drawn up by the CLCS, explaining in detail how submissions concerning the outer limits are received and examined by the CLCS. The whole procedure can be summarised as follows: beginning with a submission by a coastal state, followed by the subcommission’s examination of this submission and the final consideration of the recommendations by the full CLCS.

This complicated procedure, together with the comprehensive provisions of Article 76, was supposed to enable States to determine the outer limits of the continental shelf beyond 200 NM in an accurate manner, and consequently to diminish any uncertainty in regard to the location of the outer limits. However, as shown in practice, due to the heavy workload of the CLCS, a State currently can wait more than a decade to receive the recommendations. As a result, the outer limits of continental shelves beyond 200 NM can remain undetermined for years, rendering the determination of where the national jurisdiction ends impossible. Whilst several measures were taken to speed up the review of submissions, it does not appear to increase the work efficiency of the CLCS. In 2025, two new submissions have been lodged and three new recommendations have been made.[5] Compared with the previous CLCS working schedule, this does not indicate a substantial improvement of work efficiency.

This is upsetting for States who act in conformity with the LOSC and the CLCS regulations, especially when witnessing the unilateral claim by the United States (US) to the continental shelf beyond 200 NM as a non-party to the LOSC in 2023.[6] The US claimed that it ‘has delineated the outer limits of its extended continental shelf consistent with Article 76’,[7] which, in its opinion, reflects customary international law. The US also stated that it ‘prepared a package of data and documents on its continental shelf limits for submission’[8] to the CLCS and was ‘open to filing its submission package with the Commission as a non-Party to the Convention’.[9] For the validity of the outer limits claimed by the US, since it has not submitted to the CLCS and consequently has received no recommendations from the CLCS, according to LOSC, Article 76(8), the outer limits claimed by the US cannot become final and binding as they are clearly not established on the basis of the CLCS recommendations. Not surprisingly, this unilateral claim was strongly opposed to by parties to the LOSC. For instance, the Russian Federation criticised ‘the selective approach of the United States towards the provisions of international law where it emphasises its rights while completely disregarding its obligations’.[10] The obligations referred to seem to include: first, submission to the CLCS according to Article 76(8); second, make payments or contributions in kind in respect of the exploitation of the non-living resources of the continental shelf beyond 200 NM according to Article 82. Such objections are predictable and, if such a unilateral claim could be legitimised, it would seem outrageously unfair for States who have awaited recommendations from the CLCS for years.

The legitimacy of the unilateral claim can be further challenged from two aspects. First, it is debatable whether Article 76(2)-(7) forms part of customary international law. In judicial practices, regarding Article 76, the International Court of Justice (ICJ) only found that Article 76(1) has formed part of customary international law,[11] and the ICJ did not ‘decide whether other provisions of Article 76 of UNCLOS form part of customary international law’.[12] It is therefore questionable whether Article 76(2)-(7) has formed customary international law as argued by the US. Second, the absence of a formal submission to the CLCS would negate the unilateral claim to the continental shelf beyond 200 NM. As emphasised by the ICJ, submission to the CLCS constitutes a procedural precondition for the identification of an entitlement to the continental shelf beyond 200 NM. In the Nicaragua v. Colombia Case (2012), the ICJ observed that, as Nicaragua had only submitted preliminary information to the CLCS instead of a formal submission,[13] Nicaragua could not establish ‘a continental margin that extends far enough to overlap with Colombia’s 200-nautical-mile entitlement to the continental shelf, measured from Colombia’s mainland coast’.[14] Consequently, when dispute arises, the absence of a formal submission to the CLCS can be used to refute a unilateral claim.

Overall, even though the CLCS procedure can be time-consuming, it is still of significance because it guarantees the accurate application of Article 76, and restricts the abuse of the LOSC for the benefit of a single State.

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[1] United Nations Convention on the Law of the Sea (adopted 10 December 1982, entered into force 16 November 1994) 1833 UNTS 397 (LOSC).

[2] For instance, the breadth of territorial sea and exclusive economic zone is determined by distance. LOSC, Article 3: ‘Every State has the right to establish the breadth of its territorial sea up to a limit not exceeding 12 nautical miles, measured from baselines determined in accordance with this Convention.’ LOSC, Article 57: ‘The exclusive economic zone shall not extend beyond 200 nautical miles from the baselines from which the breadth of the territorial sea is measured.’

[3] See LOSC, Annex II, Article 3.

[4] Rules of Procedure of the Commission on the Limits of the Continental Shelf, Twenty-first session, UN Doc CLCS/40/Rev.1, 17 April 2008 (Rules of Procedure).

[5] See Submissions, through the Secretary-General of the United Nations, to the Commission on the Limits of the Continental Shelf, pursuant to article 76, paragraph 8, of the United Nations Convention on the Law of the Sea of 10 December 1982 <https://www.un.org/depts/los/clcs_new/commission_submissions.htm>.

[6] See United States Department of State, U.S. Extended Continental Shelf Project, ‘The U.S. ECS’ <https://www.state.gov/the-us-ecs/>.

[7] United States Department of State, U.S. Extended Continental Shelf Project, ‘The U.S. ECS’, Executive Summary – Regional Summaries and List of Geographic Coordinates, 6 <https://www.state.gov/wp-content/uploads/2025/02/ECS_Executive_Summary.pdf>.

[8] ibid.

[9] ibid.

[10] Remarks by Permanent Representative of the Russian Federation to the International Seabed Authority (ISA) Sergey Petrovich during the 29th Session of the ISA Council, Kingston, Jamaica, March 18, 2024 < https://mid.ru/print/?id=1940722&lang=en>.

[11] See Territorial and Maritime Dispute (Nicaragua v. Colombia), Judgment, I.C.J. Reports 2012, para 118; Question of the Delimitation of the Continental Shelf between Nicaragua and Colombia beyond 200 Nautical Miles from the Nicaraguan Coast (Nicaragua v Colombia) (Judgment) [2023] ICJ Rep 413 (Nicaragua v Colombia) paras 79, 82.

[12] ibid.

[13] Territorial and Maritime Dispute (Nicaragua v. Colombia), Judgment, I.C.J. Reports 2012, para 127.

[14] ibid para 129.

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