Extended Continental Shelf of the United States: A Landmark Announcement and Its Implications

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In December 2023, The U.S. Department of State has released information about the outer limits of its extended continental shelf (ECS). The delineation of the ECS outer limits represents the largest offshore mapping effort ever undertaken by the United States, requiring two decades of extensive collection of marine geophysical data. The outcome of this project is the delineation of the ECS, encompassing approximately 1 million square kilometers. The publishing of the U.S. ECS outer limits has significant legal and geopolitical implications.

Source: U.S. State Department, “US ECS Regions.”

Clarity on the Extent of the U.S. Jurisdiction over the Continental Shelf

The announcement clarifies the extent of the U.S. jurisdiction over the continental shelf. Under the doctrine of inherent rights, recognized as a part of customary law, a coastal State may exercise its sovereign rights over ECS ipso facto and ab initio, even pending the delineation of ECS outer limits. The exercise of sovereign rights over ECS before delineation introduces challenges due to uncertainty regarding the extent of coastal state’s jurisdiction (particularly when potential overlaps with neighboring States exist). For instance, since September 2020, the United States has been asserting jurisdiction over marine scientific research (MSR) within the limits permitted under international law over its continental shelf, including ECS. However, the specific areas under U.S. jurisdiction lacked precision; they were identified either by naming geological features in the Arctic (along the U.S.-Russia maritime boundary) such as the Chukchi Shelf, Chukchi Borderland, Canada Basin, and Nautilus Basin, or by distance from the coast in the Atlantic. Consequently, scientists intending to conduct MSR in areas potentially falling under U.S. jurisdiction had to seek confirmation from the U.S. Government on whether the seabed belongs to the Area or the U.S. ECS. This dynamic has changed with the publishing the coordinates of the outer limits in Executive Summary on The Outer Limits of the Extended Continental Shelf of the United States of America (Executive Summary).

Clarity on the Overlaps with ECS Entitlements of Canada, Japan, and The Bahamas

Furthermore, clarity has been established regarding the extent of overlaps between the U.S. ECS entitlements and those of neighboring States. The Executive Summary identifies overlaps with the ECS entitlements of Canada (in the Arctic and Northern Atlantic regions), The Bahamas (in the Southern Atlantic region), and Japan (in the Mariana Islands Region). Therefore, determining the outer limits of the U.S. ECS in these overlapping areas will depend on the delimitation of a maritime boundary with the concerned States. All the involved States may exercise jurisdiction in the overlapping areas.

Some of the U.S. maritime boundaries delimiting ECS areas were established pending delineation. Thus, the outer limits in the Eastern and Western Gulf of Mexico correspond with the continental shelf boundaries set forth in delimitation agreements the U.S. has entered with Mexico and Cuba pending delineation.

The outer limits based on the Agreement between the United States of America and the Union of Soviet Socialist Republics on the Maritime Boundary (1990 Agreement) is a special case. Although this treaty is not in force, both the United States and Russia apply it provisionally. The 1990 Agreement does not mention the outer limits or ECS, it merely defines the maritime boundary as extending north along the 168° 58′ 37″ W. meridian through the Bering Strait and the Chukchi Sea into the Arctic Ocean as far as permitted under international law (meridian line).

In its 2001 and 2015 Submissions to the Commission on the Limits of the Continental Shelf (CLCS) regarding the Arctic Ocean, Russia limited the extent of its entitlement by the meridian line. However, in the 2021 Addendum, Russia extended its entitlement beyond the meridian line, particularly on the Lomonosov Ridge and Alpha-Mendeleev Ridge Complex approaching potential U.S. ECS outer limits. Despite the absence of a binding delimitation agreement, Russia refrained from including areas clearly overlapping with the U.S. ECS (areas on the Chukchi Borderland), possibly due to political considerations.

The United States has defined its Arctic Region ECS outer limits consistent with the 1990 Agreement. In this sense, the United States has not delineated its limits on the Russian (west) side of the meridian line. Yet, a minor overlap remains between Russian and U.S. entitlements in the northern Chukchi elevation area (on the U.S. side of the meridian line). This overlap exists because a 3rd State is involved: there is also an entitlement of Canada in the same area (thus, there is a trilateral overlap).  If the United States and Canada were to agree on a maritime boundary that allocated that area to the United States, then the Agreement to apply the 1990 Agreement provisionally would prevent Russia from claiming the area east of the agreed meridian line. However, if the United States and Canada determine that this overlapping area should be awarded to Canada, then the provisions of the 1990 Agreement wouldn’t apply since there won’t be a U.S. jurisdiction. In this scenario, Russia might potentially gain a portion of the overlapping area through its negotiations with Canada.

It is worth noting that the U.S. outer limits remain subject to potential revisions. The Executive Summary specifically indicates this by highlighting that ongoing data collection and scientific research on U.S. continental margins could lead to adjustments in the published outer limits or delineating outer limits in additional areas in the future. Under international law, coastal States retain the flexibility to modify their ECS outer limits over time. For example, Russia has made several updates to its outer limits in the Arctic region. The cut-off point for updating the outer limits might be the establishment of final and binding outer limits under Article 76(8) of the United Nations Convention on the Law of the Sea (UNCLOS) or customary law and depositing them with the UN Secretary General. However, there is no clear interpretation on whether a delineating coastal State can alter these final and binding limits based on new scientific data or other compelling reasons.

Position of the U.S. Government Regarding the Submission of Data on the Outer Limits to the CLCS

The Executive Summary sheds light on the U.S. perspective concerning the delineation process and the role of the CLCS therein. The regime of the continental shelf is governed by UNCLOS and customary international law. Despite not being a State Party to UNCLOS, the United States interprets Article 76(1-7) as reflecting customary international law and thus binding upon all nations. The Executive Summary further specifies that the U.S. outer limits were established in accordance with the relevant provisions of UNCLOS (primarily referring to the formulas and constraints established by Article 76) and the CLCS Scientific and Technical Guidelines. There is no reference to the exploitability criterion of Article 1 of the 1958 Convention on the Continental Shelf to which the United States is a State Party. Therefore, the United States not only adhered to the delineation process established by Article 76 of UNCLOS, but also considered the CLCS Guidelines, which are, most likely, not a part of customary law. This demonstrates a commitment to following the process of delineation established in Article 76 (1-7) which is crucial for the international recognition of outer limits.

Moreover, the U.S. has prepared a submission for the CLCS and stands ready to submit it, regardless of its status in relation to UNCLOS. According to the U.S. position, the CLCS has the mandate to provide recommendations and advice on the outer limits of the continental shelf, even to coastal States that are not parties to UNCLOS. While there’s no legal obligation for the United States to file this submission, it represents a deliberate policy choice. The decision not to submit in 2023 might have been influenced by potential objections from States Parties to UNCLOS to the consideration of the submission by the CLCS.

Paragraph 5 (a) of Annex I to the CLCS Rules of Procedure (RoP) stipulates that if a land or maritime dispute exists, the CLCS cannot consider or qualify a submission made by any of the States concerned in the dispute. However, if all involved States provide prior consent, the CLCS may evaluate one or more submissions in the areas under dispute. Therefore, if concerned States raise objections to a submission, the CLCS might not review the submission. Also, even if objections to a U.S. submission are not considered a “land or maritime dispute,” the CLCS might still decline to review the submission in light of objections by State Parties to the admissibility of a submission by a non-Party to UNCLOS.

The Executive Summary makes is clear that both Canada and The Bahamas have indicated they would not object to the CLCS considering the U.S. submission, but it does not mention any explicit assurance from Japan. The announcement of the U.S. outer limits prompted a negative response in Russian media. The Russian Ministry of Foreign Affairs did not publish any official reaction though. The concerns expressed in Russian press mostly refer to the Arctic ECS. The prevailing position is based on the assumption that there is no customary law on the establishment of the ECS outer limits and that the United States could not unilaterally establish the outer limits without coordinating the delineation with international community. Commentators argue that the proper procedure is through the making submission to the CLCS. However, it remains uncertain whether the official Kremlin would object to a U.S. submission if it were filed with the CLCS prior to U.S. accession to UNCLOS.

Conclusions and Further Developments

The announcement of the U.S. ECS outer limits stands as a significant milestone, reflecting years of data collection and analysis. Beyond defining the extent of the U.S. ECS, this development clarifies overlaps with neighboring nations, particularly with Canada in the Arctic. This could initiate discussions between Canada and the United States regarding the longstanding Beaufort Sea dispute that involves delimitation of the territorial seas, exclusive economic zones, and continental shelf within and beyond 200 nautical miles. In 2010, the then-Canadian Foreign Affairs Minister Cannon and U.S. Secretary of State Clinton agreed that prior to engaging in negotiations on the Beaufort Sea dispute, it was important to complete the mapping of the continental shelf (referring to the ECS). With the recent announcement, both nations now have a clear understanding on the extents of their entitlements in the Arctic, paving the way for discussions on the potential maritime boundary. It remains to be seen whether the United States and Canada will hold off on a binding delimitation agreement until the CLCS issues recommendations to the Canadian submission.

The Canadian delineation process is likely to be protracted. Canada’s 2019 CLCS submission, the last from the Arctic States, sits in the end of the CLCS queue (84 out of 93), further compounded by the consideration of addenda and resubmissions in the same queue position as original submissions. This means that the CLCS will first issue recommendations for all preceding submissions along with any subsequent revisions and addenda, before turning to Canada’s 2019 submission—even if some of those revisions were submitted post-2019. As the number of revised submissions and addenda is not limited, States placed in the queue earlier than Canada can significantly delay the moment when the CLCS can start considering Canada’s Arctic Submission. Given these challenges, it is unlikely that Canada will receive recommendations within the next decade. Pending consideration of the Canadian submission by the CLCS, the Parties may consider signing the delimitation agreement in the Beaufort Sea or entering a non-binding agreement similar to the Nordic Model of Memoranda of Understanding which could be followed by a binding bilateral agreement once Canada receives favorable recommendations from the CLCS.

Another exciting development could arise if the United States files its submission to the CLCS. From a legal standpoint, this situation introduces an interesting issue, as it concerns the relationship between a treaty-based organ and a non-Party to that treaty. On one hand, conventional wisdom suggests that a non-Party might not be entitled to the resources of a treaty-based organ. However, pragmatically speaking, the international community would likely benefit more from having the U.S. outer limits scrutinized by the technical experts of the CLCS, rather than established unilaterally without any external review. Yet, States with overlapping entitlements might hold differing views, potentially opposing a non-Party nation to benefit from the UNCLOS procedures. Ultimately, the U.S.’s decision to submit data to the CLCS prior to joining UNCLOS will depend upon the prevailing political climate and the potential reactions from other nations.

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Coalter Lathrop says

January 20, 2024

Thank you, Ekaterina, for this concise and insightful piece. I'll leave the same comment here as I left for Khaled Elmahmoud, which imagines the state of affairs if the US does not accede to the Convention and the CLCS declines to make recommendations on the US ECS claim.

You touch, glancingly, upon this "third best" (my words) possibility with references to delimitation agreements in the Gulf of Mexico, a possible bilateral agreement with Canada in the absence of CLCS recommendations, and the Nordic Model.

Here it is:

In the not unlikely event that the US does not accede to the Convention (possibly ever, unfortunately) and the Commission does not make recommendations, where might the US claim end up?

Would it be subject to perpetual and universal uncertainty or could it live (perhaps uncomfortably) in a web of bilateral relationships based in the "logic of opposability" (borrowing from E Bjorge's 2021 piece in BYIL)?

Although there is no obligation to do so, it seems that interested states could make their own assessments of the US claim (assuming the US is willing to share the whole of the "data and other material" on which the claimed limits are based), and respond or act accordingly thereby signalling agreement or objection. That is, individual states could step into the shoes of the Commission and "check the math".

With agreement (partial or total), the US claim (or part of it) may be opposable to the agreeing state(s) (only). With objection (tacit or express), the US claim would remain a non-opposable unilateral act with respect to objecting states.

I was struck by the number of current and former Commissioners who provided assistance on the US claim (14 from 14 different countries) [p 13 of the executive summary]. This, alone, says nothing about agreement at the state level, but it does point to the capacity of many states (from Malaysia to Mexico to Mozambique, from Scandinavia to the tip of South America) to undertake a rigorous assessment of the underlying scientific and technical data used by the US to assemble its claimed outer limit.

Ideally, the US accedes and the Commission provides recommendations, etc. That isn't where we are.

Second best, the Commission provides recommendations on a non-party submission.

Perhaps the above represents the third best outcome for the purposes of certainty and stability in a less-than-ideal world?

Ekaterina Antsygina says

January 20, 2024

Dear Coalter (if I may), thank you for your insightful comment.

I share hope that the United States will submit their data to the CLCS (and that it will be considered). However, this decision will likely depend on factors such as the political climate in the U.S. and the potential reactions from other states. And the recent announcement regarding the outer limits and the publication of the Executive Summary may serve as a strategic move to check the reactions of other nations.

The U.S. outer limits won't be final and binding unless they are based on the recommendations of the CLCS. Nevertheless, they might still achieve international recognition over time. An interesting aspect to consider is the implication of silence from other states The lack of contestation from other states could imply tacit acceptance, which could work in the U.S.'s favor. However, the U.S. should be transparent on HOW the outer limits were established. If other states request access to the full U.S. submission to review the scientific basis behind the outer limits, refusal to provide this information could undermine claims of universal recognition.

Publishing the prepared submission might be beneficial for the U.S.: it would allow the U.S. to contend that, given the availability of all scientific data for scrutiny and the absence of objections, the U.S. outer limits should be rapidly recognized at the international level.

Regarding the involvement of CLCS experts in preparing the U.S. submission, I believe it doesn't necessarily imply acceptance by their nations, as experts operate in their own capacity (Rule 11 RoP). The participation of current or former CLCS members might suggest that the U.S. took very seriously compliance with Article 76 and the CLCS Guidelines. However, the extent of “assistance relating to extended continental shelf analysis and documentation” remains unclear. It's possible that experts contributed only to specific aspects of the U.S. submission or that some of them may not concur with the U.S. government's conclusions on the outer limits.

Mark Seidenberg says

January 21, 2024

I note you State that Paragraph 5 (a) of Annex I to the CLCS Rules of Procedure (RoP) stipulate that if a land or maritime dispute exists, the CLCS cannot consider or qualify a submission made by any of the states concerned in the dispute.

It was on 1 August 1850 at 8:30 pm the British Royal Navy took formal possession of the Plover Group (in year 1850 consisted of 4 islands, including both Cooper Island and Martin Island) that lie east of Plover Point on the Arctic coast of Alaska.

During the night of drafting the Alaska Treaty on 29 - 30 March 1867 (n.s.),William Hunter (2nd Assistant U. S. Secretary of State) informed the other drafters that the U.K. was the sovereign of the Plover Group to the north of Russian America.

During the period of 13 March - 12 April 1930, Samuel Wittermere Boggs (Geographer of the United States Department of State) held talks with William Eric Beckett (2nd Legal Advisor of the British Foreign Office) at The Hague, Netherlands which gave a concession of Machias Seal Island of the Western Seal Islands to New Brunswick for a British concession of the Plover Group as an Imperial Question. The concession offer was rejected by the British Foreign Office because Boggs did not want to handle it by a Treaty.

In August 1938, Boggs tried the concession offer again without a treaty with the Federal Government of Canada as an non-Imperial Question. The Canadian Government also rejected that concession offer by Boggs. Boggs did not return to Ottawa until 31 March 1944.

In July 1958 at Ottawa, Canada, W. A. C. Bennett (Premier of British Columbia) tells POTUS Ike Eisenhower he wanted the Plover Group attached to B.C. so British Columbia could become an "Arctic Power" at the same time he stated the Canadian Sector Theory was a violation of International Law.

Would you take the date of 19 December 2023 as a taking against the Estate of Barna Norton of Jonesport, Maine, and a trigger to block the effective claim of an Arctic Extended Continental Shelf because it created a dispute of the Plover Group because they were transferred to Canada on 1 September 1880?

Mark Seidenberg says

January 21, 2024

I have been ask for a source related to the events of 1 August 1850 at 8:30 pm which William Hunter raised on the 29 - 30 March 1867 Alaska Treaty drafting. Since the Arctic Blue Book for 1851 is hard to come by, the following is a secondary source would be a helpful read.

THE JOURNAL OF ROCHFORT MAGUIRE 1852 - 1854: Two Years At Point Barrow, Alaska, Aboard HMS PLOVER In Search For Sir John Franklin, Volume II, edited by John Bockstoce, (The Hakluyt Society, 1988), Appendix Two [T. E. L. Moore's boat expedition to Point Bartow in 1850] at page 465.

Mark Seidenberg says

January 21, 2024

It was news to me until today that during the year of 2010 both U. S. Secretary of State Clinton and Canadian Foreign Minister Cannon "agreed" that "prior to engaging in negation on the Beaufort Sea dispute it was important to complete the mapping of thr continental shelf(referring to the ECS).

Please inform be of the effective date of this agreement and the duration of said agreement and the form of the agreement. Was Angus King given notice of that agreement, because of the issue linkage that both Samuel Wittermere Boggs and William Eric Beckett agreement of March 1930 at The Hague, Netherlands?