The ITLOS Advisory Opinion on Climate Change: Selected Issues of Treaty Interpretation

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Introduction

This post analyses selected treaty interpretation issues in the ITLOS Advisory Opinion on Climate Change, delivered on 21 May 2024. The post does not seek to summarise nor address all issues raised by the Advisory Opinion. Instead, the aim is to analyse certain issues of treaty interpretation that arose at numerous points in the Advisory Opinion. Specifically, I consider ITLOS’ approach to the interpretation of ‘necessary’ measures under Articles 194(1) and 194(5) of the UN Convention on the Law of the Sea (UNCLOS) and the limits placed on States’ discretion; ITLOS’ approach to obligations of a continuing nature; the interpretation of obligations under UNCLOS in light of a precautionary approach; and the use of other international instruments to inform the meaning of key terms in UNCLOS article 194(5).

The aspects of the Advisory Opinion discussed below provide evidence of, as Roland Holst has put it, UNCLOS courts and tribunals adopting ‘a contextual and systemic approach to interpretation; linking rights to corresponding obligations that are informed by the object and purpose of the Convention at large, its overall balance of interests, and sometimes also relevant obligations under general international law’ (Rozemarijn J Roland Holst, Change in the Law of the Sea: Context, Mechanisms and Practice (Brill Nijhoff 2022) 311–12). More generally, the aspects of the Advisory Opinion discussed below support the argument developed by Nguyen that UNCLOS courts and tribunals perform a wider ‘governance function’, whereby, beyond settling discrete disputes, they are ‘expected to provide normative guidance to States in implementing the Convention in order to safeguard the uniformity and integrity of the Convention’ and to ‘“endorse” and protect the legal order that has been set up by the Convention … they become the institutional guardians of the UNCLOS legal regime’ (Lan Ngoc Nguyen, The Development of the Law of the Sea by UNCLOS Dispute Settlement Bodies (CUP 2023) 285–87).

‘Necessary’ Measures and Limits on States’ Discretion

The issue of the meaning of ‘necessary’ measures first arose in ITLOS’ analysis of Article 194(1) of UNCLOS which provides, insofar as relevant for present purposes:

States shall take … all measures … that are necessary to prevent, reduce and control pollution of the marine environment from any source, using for this purpose the best practicable means at their disposal and in accordance with their capabilities…

Interpreting this provision, ITLOS noted that while:

The word “necessary” ordinarily means “indispensable”, “requisite” or “essential”. In the context of this provision, “necessary” should be understood broadly. Such understanding is consistent with the expansive scope of the obligation under article 194, paragraph 1, implied by words such as “all” measures or “any” source. It is further supported by the inclusive definition of “pollution of the marine environment” set forth in article 1, paragraph 1, subparagraph 4, of the Convention. Accordingly, necessary measures include not only measures which are indispensable to prevent, reduce and control marine pollution but also other measures which make it possible to achieve that objective. ([203], emphasis added).

ITLOS noted that while Article 194(1) of UNCLOS ‘does not provide for any specific criteria as to what constitutes necessary measures’, this did not mean States enjoyed unlimited discretion, ‘[r]ather, necessary measures should be determined objectively’ ([205]–[206]). The Tribunal then set out ‘various factors States should consider in their objective assessment of necessary measures to prevent, reduce and control marine pollution from anthropogenic GHG emissions’, including ‘the science … International rules and standards relating to climate change … [and] available means and capabilities of the State concerned’ ([207]). Interpreting the references in Article 194(1) to States’ obligation to use ‘the best practicable means at their disposal and in accordance with their capabilities’, ITLOS acknowledged that ‘the scope and content of necessary measures may vary depending on the means available to States and their capabilities, such as their scientific, technical, economic and financial capabilities’ ([225]). Nevertheless, ITLOS sought to contain such flexibilities, emphasising that these references ‘should not be used as an excuse to unduly postpone, or even be exempt from, the implementation of the obligation to take all necessary measures under article 194, paragraph 1’ ([226], see also [229] ‘All States must make mitigation efforts’).

ITLOS returned to the meaning of ‘necessary’ measures when it considered UNCLOS Article 194(5), which requires States to take ‘measures … necessary to protect and preserve rare or fragile ecosystems as well as the habitat of depleted, threatened or endangered species and other forms of marine life’. While the provision ‘does not provide specific criteria for determining what measures are “necessary”’, ITLOS again found that ‘“necessary” … should be understood broadly’ to include ‘those [measures] which make it possible to achieve’ the permissible objective ([402]). Here ITLOS again addressed the limits on States’ discretion, holding that:

the obligation imposed by article 194, paragraph 5, of the Convention may call for specific measures, such as the enactment and enforcement of laws and regulations or the undertaking of monitoring and assessment … These measures are context-specific and call for objectively reasonable approaches to be taken on the basis of the best available science. Their implementation depends on the relevant domestic legal system and allows for the exercise of discretion. However, States do not have absolute discretion with respect to the action that is required. As stated by the Seabed Disputes Chamber in the Area Advisory Opinion, a “State must take into account, objectively, the relevant options in a manner that is reasonable, relevant and conducive to the benefit of mankind as a whole. It must act in good faith, especially when its action is likely to affect prejudicially the interests of mankind as a whole” ([405], emphasis added).

Obligations ‘of a continuing nature’

Another recurrent theme in the Advisory Opinion is that ITLOS found several of the applicable obligations are ‘of a continuing nature’ and require ongoing efforts from States. For example, in relation to the general obligation under UNCLOS Article 197 to cooperate in elaborating international rules, standards, practices and procedures for the protection and preservation of the marine environment, ITLOS noted that:

The obligation … is of a continuing nature. … The adoption of a particular treaty, such as the UNFCCC or the Paris Agreement, does not discharge a State from its obligation to cooperate, as the obligation requires an ongoing effort on the part of States in the development of new or revised regulatory instruments, in particular in light of the evolution of scientific knowledge. ([311]; see also [273]).

Ultimately, considering the obligations on cooperation in section 2 of Part XII of UNCLOS,  ITLOS found ‘that articles 197, 200 and 201, read together with articles 194 and 192 of the Convention, impose specific obligations on States Parties to cooperate, directly or through competent international organizations, continuously, meaningfully and in good faith in order to prevent, reduce and control marine pollution from anthropogenic GHG emissions’ ([321] (emphasis added), see also [319]). Similarly, ITLOS found that the obligations regarding monitoring of marine pollution under Article 204 of UNCLOS ‘are continuing in nature, in that monitoring and surveillance must be ongoing’ ([346)].

A related aspect of the Advisory Opinion is that ITLOS found that what was required of States by certain obligations could change over time. For example, in analysing the nature of the obligation under Article 194(1), as an obligation to act with due diligence, ITLOS noted that:

In the words of the Seabed Disputes Chamber in the Area Advisory Opinion, due diligence is a “variable concept” … the standard of due diligence varies depending on the particular circumstances to which an obligation of due diligence applies. There are several factors to be considered in this regard. They include scientific and technological information, relevant international rules and standards, the risk of harm and the urgency involved. The standard of due diligence may change over time, given that those factors constantly evolve. [(239); see also [317]].

Similarly, ITLOS noted that the content of the general obligation in Article 192 of UNCLOS to protect and preserve the marine environment, as a due diligence obligation, ‘may vary over time’ ([397]). ITLOS also observed that ‘the conservation of living resources and marine life, which falls within the general obligation to protect and preserve the marine environment, requires measures that may vary over time depending on the activities involved and the threats to the marine environment’ ([409]).

Interpretation in light of a Precautionary Approach

At several points in the Advisory Opinion ITLOS interpreted the relevant obligations in light of a precautionary approach. This is perhaps unsurprising given that UNCLOS courts and tribunals have previously done so (see eg 2011 Seabed Advisory Opinion [131]–[135]). For instance, in considering the obligation under Article 194(1) to take measures ‘necessary to prevent, reduce and control pollution of the marine environment’, ITLOS observed that:

in determining necessary measures, scientific certainty is not required. In the absence of such certainty, States must apply the precautionary approach in regulating marine pollution from anthropogenic GHGs. While the precautionary approach is not explicitly referred to in the Convention, such approach is implicit in the very notion of pollution of the marine environment, which encompasses potential deleterious effects. ([213], see similarly [242]).

Similarly, in interpreting the obligation to conduct an environmental impact assesment in relation to planned activities under Article 206 of UNCLOS, ITLOS held that while the terms used in the provision ‘“contain an element of discretion for the State concerned”’, that discretion was limited, including as ‘the precautionary approach may restrict the margin of discretion on the part of the State concerned’ ([361], quoting South China Sea Arbitration Award [948]). ITLOS also found the precautionary approach to be implied by the use of ‘may’ in the obligation under Article 196(1) to ‘take all measures necessary to prevent, reduce and control pollution of the marine environment resulting from … the intentional or accidental introduction of species, alien or new, to a particular part of the marine environment, which may cause significant and harmful changes thereto’ ([434]).

Interpretation of Article 194(5) in light of other Instruments

The Advisory Opinion consolidates the approach of interpreting key terms in Article 194(5) of UNCLOS in light of other relevant international instruments, first developed in the South China Sea Arbitration Award (compare South China Sea Award [945] and [956]–[957]).  As noted above, the obligation in Article 194(5) concerns ‘measures … necessary to protect and preserve rare or fragile ecosystems as well as the habitat of depleted, threatened or endangered species and other forms of marine life’, however UNCLOS does not define these terms ([403]). In summary, ITLOS, similarly to the South China Sea Tribunal, interpreted the term ‘ecosystem’ in light of the definition in the Convention on Biological Diversity (CBD) ([169] and [403]); interpreted the term ‘habitat’ in light of the definition in the CBD ([404], a point not addressed by the South China Sea Award but see Churchill, Lowe and Sander (2022) 721–22); and referred to the appendices of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) to guide what would count as a ‘depleted, threatened or endangered species’ ([404]).

Conclusion

The ITLOS Advisory Opinion significantly advances the existing environmental jurisprudence of UNCLOS courts and tribunals. In an introductory part of the Advisory Opinion, concerning ‘the relationship between the Convention and external rules’, ITLOS observed that ‘coordination and harmonization between the Convention and external rules are important to clarify, and to inform the meaning of, the provisions of the Convention and to ensure that the Convention serves as a living instrument’ ([130]). While this post has not covered all aspects of the Advisory Opinion, the aspects it has addressed suggest that ITLOS employed ‘a contextual and systemic approach to interpretation’ (Roland Holst, ibid), construing the relevant obligations in their wider context, and in a manner that will enable the Convention to effectively respond to the pressing challenge of climate change.

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