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What is the ECS and how are its limits determined?

See the About ECS section.

Where is the U.S. ECS and how big is it?

See the U.S. ECS section.

What other countries have ECS?

More than 75 countries have delineated their ECS limits. The ECS limits asserted by coastal States can be found on the Commission on the Limits of the Continental Shelf (CLCS) website  of the UN Division for Ocean Affairs and the Law of the Sea.

Will any of these countries have overlapping ECS with the United States?

The United States has potentially overlapping ECS areas with several neighboring countries, including The Bahamas, Canada, and Japan.  In areas of overlapping ECS, the United States and its neighbors will need to establish maritime boundaries in the future.  In other areas, the United States has already established ECS boundaries with its neighbors, including with Cuba, Mexico, and Russia.

What is the Commission on the Limits of the Continental Shelf (CLCS)?

The CLCS is an expert body established under the 1982 UN Convention on the Law of the Sea. It consists of 21 members who are experts in geology, geophysics, or hydrography and serve in their personal capacities. The purpose of the CLCS is to review the ECS limits of coastal States and make recommendations to those States on the location of their ECS limits.  While the CLCS meets at the UN Headquarters in New York, it is an independent entity created under the Convention. The CLCS’s website is available here .

Do continental shelf rights depend on receiving recommendations from the CLCS?

No. The CLCS reviews the ECS limits submitted to it by coastal States and makes recommendations to those States on the location of its ECS limits.  The CLCS does not approve or grant ECS to coastal States.

Do the U.S. continental rights depend upon accession to the Law of the Sea Convention?

No. Customary international law, as reflected in the Convention, confers rights and obligations relating to the continental shelf on all coastal States, including non-Parties to the Convention such as the United States. This view is well supported in international law. The International Court of Justice, for instance, has repeatedly concluded that Article 76(1) is part of customary international law. Article 76(1) provides that the continental shelf extends to “the outer edge of the continental margin or to a distance of 200 nautical miles,” whichever is further. To implement Article 76(1), paragraphs 2 through 7 of Article 76 set forth the detailed rules for determining the precise outer limits of the continental shelf in those areas where the continental margin extends beyond 200 nautical miles. Like other countries, the United States is using paragraphs 1 through 7 of Article 76 to determine its continental shelf limits and considers these provisions to reflect customary international law. Accordingly, the United States respects the continental shelf limits of other countries that abide by Article 76.

Can the CLCS determine maritime boundaries between neighboring countries?

No. The mandate of the CLCS pertains to ECS outer limits, which differ from maritime boundaries. ECS outer limits must be determined for each coastal State in accordance with the provisions of Article 76 of the Convention, whereas maritime boundaries are needed in situations where the ECS limits of neighboring countries overlap with one another. The CLCS has no mandate to establish maritime boundaries or resolve boundary disputes between neighboring countries, nor can it make any decisions that will prejudice the future resolution of such maritime boundaries. Any boundary disagreements must be resolved between the States themselves.

U.S. Department of State

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