Established by the United Nations Convention on the Law of the Sea (UNCLOS), the International Seabed Authority (ISA) is responsible for administering resources in the Area, including regulating Deep Sea Mining (DSM) activities (art. 156 UNCLOS). The role of the ISA and the DSM regime is amended and elaborated on in the 1994 Implementation Agreement on Part XI of UNCLOS. 

In 2021, Nauru invoked the “two-year rule” which formally requested the ISA to finalise exploitation regulations by 2023 (s 1(15)(b) Annex to the Implementation Agreement). The ISA has continued to negotiate exploitation regulations, but as at the close of its latest session in July 2025, no regulations have been agreed upon. Despite the Implementation Agreement permitting applications for exploitation contracts upon expiration of the two-year rule (s 1(15)(c) Annex to the Implementation Agreement), the international community’s understanding of the potential impacts of DSM exploitation has evolved over time, resulting in some States calling for a “moratorium”, “precautionary pause”, or a total ban on DSM. On the other hand, some States are ready to commence DSM exploitation activities.

Against the backdrop of the stalled negotiations, in an Executive Order of 24 April 2025, the United States has sought to expedite the process for reviewing and issuing seabed mineral exploration licences and commercial recovery permits, in areas beyond national jurisdiction under the Deep Seabed Hard Mineral Resources Act (DSHMRA). This resulted in The Metals Company submitting applications for two exploration licences and one commercial recovery permit under the DSHMRA. The United States has also recently announced a bilateral cooperation arrangement with the Cook Islands on “cooperation to advance scientific research and the responsible development of seabed mineral resources”.

On 23 July 2025, the International Court of Justice (ICJ or the Court) issued its 140-page advisory opinion on the Obligations of States with respect to Climate Change. This post considers four of the Court’s key findings that could be relevant to the ongoing debate regarding the regulation of DSM exploitation activities in the Area, including the adoption of appropriate regulations or implementing a moratorium or precautionary pause.

The interpretation of UNCLOS and the Implementation Agreement in light of the Advisory Opinion

The Court emphasised the importance of the United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement’s context, object, and purpose in clarifying States’ obligations (in particular the UNFCCC’s objective of “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system” and the temperature goal). For example, the Court considered that the UNFCCC’s “overall objective constitutes the object and purpose of the Paris Agreement, with the temperature goal providing a means for achieving this object and purpose” (para. 225). The Court’s interpretation of the climate change treaties, relying on provisions not framed as obligations, potentially places greater emphasis on context, object, and purpose, rather than ordinary meaning. Judge Tladi in his Declaration acknowledged that “[w]hile all elements of the general rule of interpretation, i.e. ordinary meaning, context and object and purpose, play an important role in the single combined operation of interpretation, in this case the element of object and purpose plays a particularly important role” (para. 20).

In the context of interpreting UNCLOS and States’ obligations concerning DSM activities, the Court’s approach in elevating the importance of object and purpose relative to ordinary meaning, could see Part XII of UNCLOS on the protection and preservation of the marine environment being used by the ISA and States (and potentially courts or tribunals) to interpret the DSM framework. Notwithstanding the elaborate framework for DSM in Part XI of UNCLOS and the Implementation Agreement, the ISA or States parties could raise the importance of Part XII’s object and purpose to curtail DSM activities, including giving greater support to calls for a moratorium or precautionary pause. 

Relationship between UNCLOS, the Implementation Agreement, and Customary International Law

The Court found that lex specialis applies where there is an ‘actual inconsistency’ between the rules in question or “a discernible intention that one provision is to exclude the other” (para. 167). On the first point, the Court noted that the climate treaties “themselves contain references to other rules and principles”, which shows that States recognized the relevance of such rules (para. 168). With respect to the second point, the Court acknowledged that even though “the climate change treaties have been carefully negotiated and represent a calibrated set of interrelated rules” and “are the principal instruments addressing the global problem of climate change”, that does not convey an intention to exclude other rules (paras. 168-169). The Opinion does not delve into any other evidence of the parties’ intentions. 

As with the climate treaties, whether or not an ‘actual consistency’ exists between customary international law (CIL) and the DSM provisions largely depends on whether those can be interpreted harmoniously, as discussed below. Furthermore, the Court’s Opinion entails that the elaboration of specific rules on DSM in the treaties and subsequently by the ISA does not entail an intention to exclude the applicability of other rules. 

With respect to the content of CIL, the Court found that the duty to prevent significant harm to the environment (‘duty to prevent’) and the duty to cooperate for the protection of the environment (‘duty to cooperate’) are applicable to climate change (paras. 131-142). The conclusion that the duty to prevent “is not confined to instances of direct cross-border harm and that it applies to global environmental concerns” should equally apply in the Area. 

The Court found that the duty to prevent is “intrinsically linked to the duty to prevent” (para. 141). Cooperation was said to be “an essential element in the protection of the environment” particularly with respect to “the conservation and management of shared resources”, which is equally applicable to the Area, ‘the common heritage of mankind’. 

As to the relationship between CIL and the climate treaties, the Court stressed the principle of systemic integration, and that applicable rules “should, to the extent possible, be interpreted so as to give rise to a single set of compatible obligations”, as also reflected in the VCLT Article 31(3)(c) (paras. 165, 309-311). The Court opined that treaties and their implementation can inform the content of CIL while the latter can inform the interpretation of the former (para. 313, for more on this see Arato and Uriburu). 

The Court noted that these “independent obligations … do not necessarily overlap”, but considered “that, at the present stage, compliance in full and in good faith by a State with the climate change treaties, as interpreted by the Court (see paragraphs 174-270 above), suggests that this State substantially complies with the general customary duties to prevent significant environmental harm and to co-operate” (para. 314). Applied to UNCLOS State parties in the context of DSM, and considering that both duties are inherent in UNCLOS, it is thus not entirely clear what CIL adds to their treaty obligations in practice, unless the obligations do not coincide. In this context, it is interesting to note that some States pushing for the exploitation of the seabed took the view before the Court that the duty to prevent imposes on States obligations that are more stringent than the climate treaties (e.g., Nauru written comments, paras. 11, 47, 48). In principle, the argument could equally apply to the relationship between UNCLOS rules on DSM and CIL. Such a result, however, may revive arguments of ‘actual inconsistency’ and lex specialis. 

Harmonious interpretation is particularly important for the interpretation of UNCLOS, because State parties are under an obligation to implement any other environmental treaties (e.g., The Convention on Biodiversity) “in a manner consistent with the general principles and objectives” of UNCLOS (Article 237(2)). Similarly, a court or tribunal established under the dispute settlement provisions of UNCLOS may only consider “other rules of international law” insomuch as they are “not incompatible” with UNCLOS (Article 293). 

As for non-parties considering DSM, the Court’s view that treaty rules and their application inform the content of CIL, brings the customary obligations closer to the specific treaty obligations, at least with respect to the duty to prevent and the duty to cooperate (para. 315, Arato and Uriburu).

Precautionary Principle

The precautionary principle has formed a key part of the legal framework governing DSM and is a focal point in the current debate on whether exploitation activities should pause or proceed. The Court briefly considered the precautionary principle, concluding that “where applicable, [it] guides States in the determination of the required standard of conduct in fulfilling their customary duty to prevent significant harm” (para. 294). The Court also endorsed the International Tribunal for the Law of the Sea’s (ITLOS) conclusions in the Area Advisory Opinion that where there are plausible risks, “a State ‘would not meet its obligation of due diligence if it disregarded those risks’ and, in that sense, the ‘precautionary approach is also an integral part of the general obligation of due diligence’ under the duty to prevent significant harm to the environment” (para. 294, citing Area Advisory Opinion para. 131). Judge Charlesworth in her separate opinion sought to provide further clarification on the relationship between the precautionary principle and the duty of prevention (para. 4). Judge Charlesworth stressed that prevention and precaution “operate on a continuum and complement each other” (para. 4) and suggested “it is possible for a certain conduct to be initially governed by the precautionary principle, and subsequently, as greater scientific certainty is gathered in connection with the conduct in question, for the prevention obligation to apply” (para. 6).

Where DSM science remains uncertain, States are obliged to incorporate the precautionary principle into its risk assessment of any exploration or exploitation activities. Applied to UNCLOS States parties, the Court’s findings may be relied upon by States calling for a moratorium or precautionary pause on DSM exploitation activities until there is greater certainty on the potential impacts to the marine environment (for example noise and light pollution, behavioural distress to marine mammals, and the interruption of important ecological processes). The potential harm to the environment from DSM activities is more uncertain than the potential harm to the environment from anthropogenic greenhouse gas emissions. The Court’s findings on the precautionary principle could therefore play a much more significant role in the debate around DSM exploitation activities given this greater uncertainty, than it may do in clarifying States’ obligations with respect to emissions.

Due Diligence

States’ due diligence obligations (the obligation to take all necessary measures to reduce emissions) were central to the Court’s considerations. The Court concluded that the standard of due diligence with respect to climate change was stringent (para. 138), based on the fact that climate change “poses a quintessentially universal risk to all States… of a general and urgent character” (para. 137). The relevant standard for DSM activities, the risks of which are of a different nature, would have to be assessed in light of its specific characteristics, including the risks and dangers of noise and light pollution, effects on other marine ecosystems, uncertainty of impacts of DSM on carbon sequestration and deep-ocean carbon storage, untested technologies and potential risks to the environment if they fail. Furthermore, the Court placed strong emphasis on States’ regulatory due diligence, endorsing ITLOS’ findings in its Climate Change Advisory Opinion that to satisfy the due diligence obligation States must “put in place a national system, including legislation, administrative procedures and an enforcement mechanism necessary to regulate the activities in question, and . . . exercise adequate vigilance to make such a system function efficiently, with a view to achieving the intended objective” (para 281., citing ITLOS Climate Change Advisory Opinion para. 235, see also para. 282). Applied to DSM activities, even if the Implementation Agreement permits States to carry out DSM activities in the absence of agreed exploitation regulations, a State’s domestic legislation, which forms part of the due diligence assessment, could be relevant to assessing whether a State has met its stringent due diligence obligations. (para. 428). 

Further, States’ due diligence obligations are not static – “[t]he standard of due diligence may also become more demanding in the light of new scientific or technological knowledge” (para. 284). The Court also clarified that “as States develop economically and their capacity increases, so too are the requirements of diligence heightened” (para 292., Separate opinion of Vice-President Sebutinde para. 10, Joint declaration of Judges Bhandari and Cleveland para. 27)). In the context of DSM where certain “reserved areas” (for example the Clarion Clipperton Zone) are reserved for access by developing countries or the Enterprise, the Court’s findings make clear that developing States do not have a lesser standard of due diligence and are still held to “stringent” requirements, though consistent with their capabilities and national circumstances. This standard is to be assessed objectively and may therefore change (increase or decrease) over time (para. 300).

Concluding remarks

The Court’s Advisory Opinion does not directly address DSM activities. However, it is clear that the Court’s interpretation and clarification of obligations in the context of climate change could be more widely applied to other activities that may impact the environment, such as DSM. It will be interesting to see how States may seek to employ the Court’s findings at future ISA negotiations, or to hold other States accountable should they proceed with DSM activities in the absence of an agreed Mining Code. In any event, the impact of the Court’s opinion is certainly not limited to the Climate Change Treaties or GHG emissions.