NORI and TOML v. International Seabed Authority: Attempt to Undermine UNCLOS and Other Rules of International Law?
By Dominique Virgil
Published on 17 June 2026
Disclaimer: The opinions expressed in this post are the author’s own and do not reflect the view of any institution.
On 30 May 2026, Nauru Ocean Resources Inc. (NORI) and Tonga Offshore Mining Ltd. (TOML) instituted proceedings against the International Seabed Authority (ISA) before the Seabed Disputes Chamber. Both companies argued that the Authority violated requirements of due process, transparency, and fairness because it failed to explain the evidence and methodology used in its investigations into the two companies’ alleged non-compliance with their contractual and international legal obligations.
The two companies argued that the ISA allegedly violated Council Decision No. ISBA/31/C/18 and the recommendations of the Legal and Technical Commission (LTC) No. ISBA/29/LTC/5. In their requests for provisional measures, the two companies asked the Chamber to suspend the Authority’s inquiry, and prohibit the adoption and publication of any recommendation or finding arising from the inquiry.
These requests mark the first time the Chamber has received an application for provisional measures and contentious proceedings. While this request is made possible by Article 187, para. (c) Under the United Nations Convention on the Law of the Sea (UNCLOS), there is a broader challenge that should be addressed. This post argues that the challenge to the Authority’s discretion to investigate plausible non-compliance by contractors may risk undermining Member States’ obligation to exercise due diligence and the precautionary principle to prevent and reduce significant harm to the marine environment.
In the same vein, this post aims to delve into how contractors’ non-compliance may pose a risk of significant harm to the marine environment, if not mitigated, and how any contentious proceeding against measures taken by the Authority to prevent such harms undermines the Authority’s mandate under UNCLOS to ‘organise and control activities in the Area’. This post concludes that, considering international jurisprudence on marine environment and States’ responsibility, the Member States to the Authority, acting through the Authority, have acted in accordance with their legal obligation. Subsequently, it is less likely that the Chamber will reach a favourable decision for NORI and TOML on the merits. This post does not touch on potential objections to the Chamber’s jurisdiction that the Authority might raise.
Obligations of Member States of the Authority: Due Diligence Duty to Prevent Significant Harm to the Marine Environment
Articles 139(2) and 304 of UNCLOS make explicit reference to other ‘rules of international law’. Accordingly, both contractors and sponsoring States Parties are bound not only by the obligations expressly set out in UNCLOS, but also by the customary international law rules, which operate alongside and complement the UNCLOS framework.
The Chamber’s advisory opinion on the Responsibilities and Obligations of States with Respect to Activities in the Area in 2011 referred to Article 145 of UNCLOS, which says that its States Parties shall carry out ‘necessary measures … to ensure effective protection for the marine environment from harmful effects which may arise from such activities’. One way to fulfil this obligation is through the adoption of rules, regulations, and procedures by the Authority, as mandated in Annex III, Article 17, paragraph 2(f) of UNCLOS (para. 85-86).
International jurisprudence has extensively provided guidance on how this obligation can be implemented, such as through enactment of regulations, active supervision, enforcement, and correction of violations by States, as drawn from the ICJ’s Pulp Mills judgment and the Chamber’s 2011 Activities in the Area Advisory Opinion. Both ITLOS and ICJ, in their advisory opinions on climate change, reaffirmed the duty of States to prevent significant harm to the marine environment, which is a due diligence obligation under the precautionary principle. The Obligations of States in respect of Climate Change Advisory Opinion (para. 293-294) specifically outlined that States must take preventive action even when science is uncertain, and any incomplete knowledge should not cause them to delay cost-effective measures to act on plausible risks of harm to the marine environment. This obligation has been recognised as part of customary international law (para. 440 in the Obligations of States in respect of Climate Change Advisory Opinion), and is also incorporated in Part XI and Part XII of UNCLOS.
The Trail Smelter Arbitration goes further and established that States must take sufficient preventive measures, which many international instruments translated into carrying out ‘best practicable means at their disposal’. The Draft Articles on Prevention of Transboundary Harm, adopted by the International Law Commission (ILC), add further texture to the interpretation of this due diligence obligation, stating that States are expected to make reasonable efforts to understand the potential consequences of their activities (p. 154). Once informed of foreseeable risks of their activities, States must act promptly and appropriately to address them, through both policy development and enforcement (p. 154).
The Council decision authorising the inquiries and giving the power to the Secretary-General of the Authority to carry out such inquiries is consistent with the due diligence obligation to prevent significant harm to the marine environment. I argue below that the non-compliance of private actors poses a plausible risk of significant harm to the marine environment, thereby requiring early identification and mitigation measures by States acting through the Authority.
Non-Compliance Posing Plausible Risk of Significant Harm to the Marine Environment
The first report of the Special Rapporteur on due diligence in international law highlighted that the recent advisory opinions from ITLOS, ICJ, and the Inter-American Court of Human Rights clarified that due diligence is an objective standard that can be ‘stringent’ or ‘heightened’ depending on the severity of the risk and urgency of the situation. The Report placed an emphasis on the need for knowledge of the risk of harm, and specific consideration of ‘proximity and degree of risk and severity of potential harm’, and ‘the value of the interest to be protected’ (p. 41).
Scholars have also defined the criteria of significant harm to the marine environment by referring to the Food and Agricultural Organisation (FAO) framework, which include, e.g., intensity and severity of the impact, sensitivity and vulnerability of the ecosystem, recovery potential of the ecosystem to its original state, the cumulative impacts of multiple stressors to the environment, and scientific uncertainty. The incomplete knowledge of deep-sea ecosystems makes them more vulnerable to human activities, especially due to the combined effects of prior environmentally degrading activities carried out on the high seas, also known as ‘cumulative impacts’. The combination of cumulative impacts and the scientific uncertainty of deep seabed mining heightens the risk of significant harm to the marine environment.
As for the ‘value of the interest to be protected’, the Area has been recognised as the common heritage of humankind, which the States Parties to UNCLOS and the Authority must protect. The value of this interest can be seen through obligations in UNCLOS and the Part XI Implementation Agreement, under which States Parties, especially sponsoring States, serve the shared interests of all States in upholding the common heritage principle, doing so both by supporting the Authority and by independently working to ensure that entities falling under their jurisdiction comply with deep seabed mining regulations (para. 226 of the 2011 Activities in the Area Advisory Opinion).
In the context of the NORI and TOML cases in the Chamber, Greenpeace has previously underlined the connection between NORI and TOML and The Metals Company (TMC), which intended to start exploiting the minerals under the United States’ Deep Seabed Hard Mineral Resources Act of 1980. The Greenpeace article also underlined that the risk of non-compliance arises from the possibility of violating Article 137 of UNCLOS, which prohibits unilateral claims over the Area outside the Authority’s regime (p. 4). Unilateral action carried out outside of the Authority’s regime compounds the risk to the marine environment due to the lack of monitoring and surveillance procedures and authority, the non-uniform environmental standards and mitigation strategies, and single ownership of knowledge of the deep-sea ecosystem. The risks of deep-seabed activities, as exemplified by prior research, though not fully understood, warrant coordinated, science-based international oversight, which countries had strived to do through the establishment of the Authority during the UNCLOS negotiation.
Based on the assessment above, contractors’ non-compliance may pose a plausible risk of significant harm to the marine environment, a situation that UNCLOS and the Part XI Implementation Agreement seek to avoid through the Authority’s role. In this context, the cumulative effects of existing activities in the high seas, coupled with scientific uncertainty and the interest of all humankind that the Authority is mandated to safeguard, are further amplified through possible unilateral actions which heightened the risks of significant harm to the marine environment. Steps taken by the Council to authorise the inquiry process of contractors can be characterised as efforts to identify the risk, which is a necessary first step to determine the corresponding mitigation measures to address such risk.
States Parties under articles 139 and 153 para. (4) of UNCLOS are obliged to assist the Authority in exercising control over activities in the area (2011 Activities in the Area Advisory Opinion, para. 122), and ensuring compliance of the contractors is one of the established forms of control (2011 Advisory Opinion, para. 124). The Chamber further specified in the Advisory Opinion that this obligation involves the sponsoring State objectively weighing the available options in a way that is sensible, pertinent, and serves the collective interest of mankind, and carry out such measures with good faith (para. 230). The Sponsoring State is also obliged to ensure that the contractors meet the requirements set out in their contracts with the Authority and comply with its obligations under UNCLOS (para. 233).
Aside from this treaty-based obligation, assisting the Authority to secure compliance of contractors with relevant provisions of this Part and the Annexes relating thereto, and the rules, regulations, procedures of the Authority, and the plans of work approved by the Authority, is arguably in line with the broader obligation of States under the precautionary principle and the duty to prevent significant harm to the environment. Since the Council adopted the decision to initiate an inquiry into non-compliance by the two contractors, States that are members of the Council have acted in accordance with their mandate and legal obligations.
Possible Relation with States Responsibilities under International Law
Article 214 of UNCLOS requires States to take necessary measures, including through implementing the international rules and standards through the Authority to ‘prevent, reduce and control pollution of the marine environment arising from or in connection with seabed activities subject to their jurisdiction’. ITLOS, in its 2024 Advisory Opinion concerning climate change, clearly held that failure to carry out these measures may trigger its international responsibility (para. 286), while the ICJ, in its Obligations of States in respect of Climate Change Advisory Opinion, held that in the context of greenhouse gas emissions, a State’s failure to take appropriate actions to prevent significant harm to the marine environment may constitute an internationally wrongful act attributable to the State (para. 427-432).
Applying the courts’ interpretation in the current context, the adoption of the resolution enabling the non-compliance inquiry by the Council can be classified as a necessary measure by the Council’s Member States to prevent harm to the marine environment arising from seabed activities carried out by the contractors. There is always a possibility that any refusal or interference by any Member State with the effective implementation of the Authority’s role in controlling and governing the Area, including by ensuring that contractors comply with UNCLOS and other relevant regulations, may lead to international responsibility for the State.
Conclusion: A Likelihood of Unfavorable Decision against NORI and TOML
While awaiting the Chamber’s determination of the merits of the case brought by NORI and TOML, the contractors and their Sponsoring States were not released from their obligations to maintain vigilance over their activities in the Area. They still possess legal obligations to ensure that their activities comply with the standards set by the Authority, and assist the Authority in carrying out its functions. Their objection to the procedural matters of the Authority’s intention to initiate the non-compliance inquiry cannot be used to justify their alleged failure to take appropriate measures to prevent harm to the marine environment, which poses risks that the Authority is mandated to mitigate.
Considering this background, it is likely that upon assessing the contractors’ and their sponsoring States’ obligations under international law, the Chamber may reach a conclusion that might be unfavorable to NORI and TOML, as well as to their sponsoring states, Nauru and Tonga, respectively.
Dominique Virgil is currently a diplomat (Third Secretary) in the Directorate of Legal Affairs and Territorial Treaties, Ministry of Foreign Affairs of Indonesia. Her work concerns the law of the sea, including maritime delimitation, maritime safety and security, the marine environment, shipping, fisheries, and the interplay between the law of the sea and the law of armed conflict. She previously worked as a researcher in Amnesty International Indonesia, focusing on palm oil and other issues relating to economic, social, and cultural rights.
She received her LL.M. from Harvard Law School in 2025 and her LL.B. (Sarjana Hukum) from the Faculty of Law, Universitas Indonesia in 2019, majoring in public international law. She received the Dean’s Scholar Prize at Harvard Law School for her work in the Law of the Sea and Honours for her Master’s Thesis on provisional measures of the International Court of Justice (ICJ) and the peremptory norms of international law, supervised by Prof. Naz Modirzadeh. She was also a research assistant to Professor Idriss Fofana, the Program on International Law and Armed Conflict (PILAC), and the Program on Law and Society in the Muslim World (PLSMW), exposing her to various aspects of international law.
She can be reached through dominique.tuapetel@gmail.com.