The United Nations Convention on the Law of the Sea
The United Nations Convention on the Law of the Sea (UNCLOS) 1982, established a comprehensive legal framework for all activities in the oceans and seas. It defines the rights and responsibilities of States regarding the use of the oceans, including maritime zones, resource management, and environmental protection, and is currently subscribed to by 170 States.
The Convention recognizes two broad parts – the part within the limits of national jurisdiction and the part outside the limits of national jurisdiction (article 1(3)) – and ascribes rights to States accordingly. Depending on the part in which a State is acting, it could exercise exclusive rights (within national jurisdiction), it could exercise freedoms, and what we would refer to as contractual rights (for want of a better description) when States act in the zones falling outside the limits of national jurisdiction. When States act on the high seas, they exercise freedoms, and when they act within the deep seabed outside the limits of national jurisdiction, they exercise what we have called contractual rights through a license granted by the International Seabed Authority (ISA) under part XI of the UNCLOS. This is because, unlike the High Seas, where States exercise freedom over resources (fishing), no such freedom exists under the UNCLOS over the mineral resources of the deep seabed beyond the limits of national jurisdiction (the Area). This highlights the fact that the UNCLOS makes a clear distinction between the High Seas (the superjacent waters beyond the limits of national jurisdiction) and the Area (the deep seabed beyond the limits of national jurisdiction).
The UNCLOS came with several innovations that could not rightly be said to have existed as customary international law (CIL) prior to its coming into force. A remarkable innovation is contained in Part XI which provides for the reservation of the resources of the deep seabed beyond national jurisdiction (Area) for all States (coastal and landlocked) as the common heritage of mankind. For the avoidance of doubt, it is clearly enacted in Part XI, inter alia, that “No State shall claim or exercise sovereignty or sovereign rights over any part of the Area or its resources, nor shall any State or natural or juridical person appropriate any part thereof. No such claim or exercise of sovereignty or sovereign rights nor such appropriation shall be recognized” (article 137). This part was implemented by 1994 Agreement relating to the Implementation of Part XI of the United Nations Convention on the Law of the Sea.
The United States and the UNCLOS
The United States of America is one of the handful of States that are not parties to the UNCLOS. Despite actively participating in its formulation, the US refused to become a party to the Convention. Nevertheless, the practice of the United States follows the UNCLOS in material respects, but on the basis that certain UNCLOS provisions reflect CIL. In relation to the deep seabed, the United States have been participating in the activities of the ISA, albeit in an observer capacity, and refrained from taking unilateral actions regarding the mineral resources of the Area in practical terms.
On 24 April 2025, however, the Trump administration signed an executive order – “Unleashing America’s Offshore Critical Minerals and Resources” – to demonstrate its intention to take unilateral action regarding the resources of the deep seabed thereby operating alongside rather than within the multilateral framework of the ISA. Following the publication of the executive order, several ISA member States, both during ISA Council and Assembly meetings, and in their individual capacities, have been expressing serious concerns about unilateral actions by any State concerning the resources of the Area. States have also been reaffirming the multilateral approach established by the UNCLOS and implemented through the ISA, which has governed activities in the Area for the past three decades.
Also, the ISA has severally commented on the legality of the actions of the US and continued to assert its exclusive rights to the governance of the Area through the multilateral framework established by the UNCLOS. There is the 30 April 2025 Statement by Ms. Leticia Reis de Carvalho Secretary-General and the FAQs on the same subject matter. Both items have also been published on our website.
The Response of the United States
In its Statement on Agenda Item 8, International Seabed Authority Assembly, 30th Session July 2025, the US said it was responding “to incorrect legal assertions concerning the legal character of the Law of the Sea Convention seabed mining provisions, as well as factually incorrect assertions concerning state practice of the United States”.
The perspective of the United States, as conveyed in the statement, is outlined in the following paragraphs.
Part XI is not Binding on the US both in Treaty and CIL
The US emphasized that it has consistently viewed UNCLOS provisions relating to traditional uses of the ocean, including freedom of navigation and overflight, as reflecting CIL binding on all States, and that it has never considered Part XI of the Convention or the 1994 Implementing Agreement to reflect CIL. On this premise, the US stated that it is not bound by the Convention rules dealing with seabed mining through the ISA. The statement referenced remarks the US has made over time on the status of the Area.
The US referenced its statement at the conclusion of the third UN Conference on the Law of the Sea in 1982, when it stated that “some speakers asserted that existing principles of international law, or the Convention, prohibit any State, including a nonparty, from exploring for and exploiting the mineral resources of the deep seabed except in accordance with the Convention. The United States does not believe that such assertions have any merit. The deep-sea-bed mining regime of the Convention adopted by the Conference is purely contractual in character.” It recalled its further comments at the conclusion of the third UN Conference on the Law of the Sea that, “Article 137 of the Convention may not as a matter of law prohibit seabed mining activities by nonparties to the Convention; nor may it relieve a party from the duty to respect the exercise of high seas freedoms, including the exploration for and exploitation of deep sea-bed minerals, by nonparties. Mining of the seabed is a lawful use of the high seas open to all States. United States participation in the Conference and its support for certain General Assembly resolutions concerning sea-bed mining do not constitute acquiescence by the United States in the elaboration of the concept of the common heritage of mankind contained in Part XI, nor in the concept itself as having any effect on the lawfulness of deep sea-bed mining.” It further referenced its 1983 response to the adoption of the Law of the Sea Convention, when then-President Ronald Reagan announced the United States’ position that the Convention “contains provisions with respect to traditional uses of the oceans which generally confirm existing maritime law and practice,” but that the United States would not sign the Convention due to “major problems in the Convention’s deep seabed mining provisions” and that “Deep seabed mining remains a lawful exercise of the freedom of the high seas open to all nations.”
The statement carefully emphasized that that the United States has been clear that its position on the Convention’s provisions relating to “traditional uses” being customary international law does not include Part XI provisions on seabed mining. In this regard, it cited the 2007 Congressional testimony of Deputy Secretary of State John Negroponte noting that “traditional uses of the oceans” does not include deep seabed mining and a statement in the 2010 Digest of United States Practice in International Law stating that “The phrase ‘traditional uses of the ocean’… is intended to exclude Part XI of the Convention concerning deep seabed mining.” The statement firmly asserted that United States state practice is clear and consistent on this matter.
For completeness, the statement declared “We would also note that participation of State Parties to the Convention in the work of the ISA is also incapable of constituting opinio juris needed for the formation of a customary international law rule, as such participation is done pursuant to treaty obligations and rights. If Part XI of the Convention genuinely constituted customary rules of law binding on all States, then all States, even non-Parties to the Convention, would have customary international law rights to participate in the work of the ISA as members. Such rights have never been recognized”.
The US Participation in the meetings of the ISA
The statement explained that as a non-party to the Law of the Sea Convention, the US has participated in ISA meetings in an observer status as an affected coastal State, to protect U.S. interests, “including those with respect to our continental shelf and exclusive economic zone adjacent to the Clarion-Clipperton Zone and other parts of the Area of potential ISA interest, and to support the development of a responsible ISA regulatory framework”. The United States therefore expressly rejected the notion that such involvement implies recognition of CIL status for the ISA or for Part XI of the UNCLOS.
The Domestic Law of the US
On the domestic front, the statement drew attention to the United States Deep Seabed and Hard Mineral Resources Act, 1980, which states that “exploration for and commercial recovery of hard mineral resources of the deep seabed are freedoms of the high seas subject to a duty of reasonable regard to the interests of other states in their exercise of those and other freedoms recognized by general principles of international law.” While stating that the United States has renewed exploration licenses under this domestic framework for decades, “the statement emphasized that the law dictates that the U.S. private sector’s deep-sea exploration and commercial recovery activities in areas beyond national jurisdiction must be undertaken with strong standards and environmental impact assessments, and those activities must not unreasonably interfere with the interests of other states in their exercise of high seas freedoms”.
The Way Forward
Reiterating its commitment to maintaining a unilateral parallel regime to the ISA, the statement concluded “The United States is focused on the responsible development of seabed mineral resources, while ensuring environmental and transparency standards are maintained. We will be deliberate and thoughtful in this approach and plan to develop this sector in a manner that contributes to a better understanding of the deep sea, including mapping and characterization, environmental information, and the economic potential of its mineral resources. We welcome further discussion on responsible seabed mineral development”.
As the exchange between the United States and the ISA persists, the coming months and years will reveal how this emerging strain on the multilateral framework for deep seabed governance is ultimately addressed.
