The Competence of the International Tribunal for the Law of the Sea in its New Advisory Proceedings on Climate Change

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On the sidelines of last year’s COP26, Antigua and Barbuda and Tuvalu concluded the Agreement for the Establishment of the Commission of Small Island States on Climate Change and International Law (‘the Agreement’ establishing ‘the Commission’). The Agreement is open to signature by all 39 members of the Alliance of Small Island States, and currently also includes Niue, Palau, Saint Lucia, and Vanuatu.

Article 2(2) of the Agreement notably empowers the Commission to request advisory opinions from the International Tribunal for the Law of the Sea (ITLOS) on issues such as the “adverse effects of climate change on the Small Island States”, bearing in mind the “fundamental importance of oceans as sinks and reservoirs of greenhouse gases (GHGs) and the direct relevance of the marine environment to the adverse effects of climate change on the Small Island States”. Following from its press release at last month’s COP27, the Commission submitted its first questions to ITLOS on 12 December 2022:

What are the specific obligations of State Parties to the United Nations Convention on the Law of the Sea (the “UNCLOS”), including under Part XII:

(a) to prevent, reduce and control pollution of the marine environment in relation to the deleterious effects that result or are likely to result from climate change, including through ocean warming and sea level rise, and ocean acidification, which are caused by anthropogenic greenhouse gas emissions into the atmosphere?

(b) to protect and preserve the marine environment in relation to climate change impacts, including ocean warming and sea level rise, and ocean acidification?

The seeming simplicity of the process for submitting this request may be contrasted with requests for advisory opinions from the International Court of Justice (ICJ). This is evident in Vanuatu’s quest to persuade a majority of the United Nations General Assembly (UNGA) to adopt a resolution asking the ICJ to determine the “obligations of States under international law to ensure the protection of the climate system and other parts of the environment for present and future generations”, and the legal consequences of breaching such obligations. As noted in this blog, both campaigns “seek the authoritative guidance of an international court on the long-neglected matter of loss and damage”.

Yet the relative straightforwardness of the process for requesting opinions from ITLOS should not obscure any legal challenges which might arise thereafter. In this light, we consider key aspects of the framing of these questions, and entertain the grounds on which some Contracting Parties to the 1982 UN Convention on the Law of the Sea (UNCLOS) might argue that the Tribunal should decline to render an opinion in the COSIS proceedings.  

The Advisory Jurisdiction of ITLOS

According to Article 138 of its Rules, ITLOS may receive advisory requests from “whatever body is authorized by or in accordance with the agreement to make the request to the Tribunal”—a framing which should be understood as referring solely to intergovernmental organizations, as former Judges Ndiaye and Treves have observed. In 2015, the Tribunal delivered the only advisory opinion that it has decided en banc, upon the request of the Sub-Regional Fisheries Commission (SRFC).

Yet it first considered whether an advisory request to the plenary Tribunal—and the specific questions posed by the SRFC—fell within the framework of “all matters specifically provided for in any other agreement which confers jurisdiction on the Tribunal”, as set out in Article 21 of its Statute [paras 46, 56, 67]. On this point, the Tribunal has attracted some criticism for an arguably expansive interpretation of its judicial function [p. 3].

Applicable Law in ITLOS Advisory Opinions

When responding to the questions posed in SRFC, the Tribunal drew from Article 293 of UNCLOS, Article 23 of its Statute, and Article 130 of its Rules to find that it is empowered in advisory proceedings to apply UNCLOS “and other rules of international law not incompatible with this Convention” [paras 55, 80, 143]. Article 293 thus enables ITLOS to apply customary rules and other uncodified sources concerning the protection of the marine environment.

As such, the query arising in the COSIS proceedings is whether rules regarding environmental law and responsibility for climate change are “not incompatible” with UNCLOS. In light of the causal link between GHG emissions and the depletion of living resources through the warming and acidification of the oceans, this must be answered in the affirmative.

This conclusion arises from the responsibility of States under Article 235 of UNCLOS to “fulfil […] their international obligations concerning the protection and preservation of the marine environment”, and to “ensure that recourse is available in accordance with their legal systems for prompt and adequate compensation or other relief in respect of damage caused by pollution of the marine environment […]” [cf. art. 1(4)]. Indeed, such questions may enable the Tribunal to “articulate the relevant climate change-related legal rights and obligations under [UNCLOS]” [Freestone, Barnes, and Akhavan, p. 172].

The Framing of Advisory Requests to ITLOS

 Yet the express references to sea level rise in the Commission’s request could invite pleadings regarding a potentially broader range of issues. These might concern the preservation of existing rights in maritime zones and the legal status of islands [Wewerinke-Singh], or obligations erga omnes under the law of the sea [Holst]. Any such issues raised in these proceedings are likely to be assessed on the basis of certain bedrock principles arising in advisory proceedings.

Firstly, as seen in Nuclear Weapons (WHO), advisory requests are circumscribed by the institutional principle of speciality. The questions posed must thus “aris[e] within the scope of the activities of the requesting agency” [para 10]. Unlike the onerous process of obtaining UNGA support for ICJ advisory requests, Article 138 of the ITLOS Rules permits any intergovernmental organization to activate the Tribunal’s advisory jurisdiction if authorized to do so by “an international agreement related to the purposes of the Convention”.

In SRFC, the Tribunal observed that questions posed in an advisory request should be “framed in terms of law” and “raise problems of international law” [para 65]. It considered that its opinion should be desirable “in order to obtain enlightenment as to the course of action [the requesting organization] should take”, “to seek guidance in respect of [the organization’s] own actions”, and to “contribute to the implementation of the Convention” [paras 76-77].

The Tribunal’s response to the questions posed in COSIS would indeed provide useful information for the activities of the Commission and the implementation of its mandate. The request filed this week seeks clarification of marine protection obligations reflected in Articles 192 and 194 of UNCLOS. This follows from Article 1(3) of the Agreement, which requires that questions submitted by the Commission “contribute to the definition […] of rules and principles of international law concerning climate change, including but not limited to the obligations of States relating to the protection and preservation of the marine environment”.

Article 1(3) of the Agreement appears to foresee subsequent questions from the Commission on responsibility for injuries arising from wrongful breaches of these obligations. Should the Commission choose to submit requests in rapid succession, there appears to be no rule restricting the Tribunal from consolidating them into a single hearing. In our view, the discretion reflected in Article 138 of the ITLOS Rules (“The Tribunal may give an advisory opinion”)—as well as Article 47’s joinder mechanism—apply as well to the form of advisory opinions. Such consolidation might serve the good administration of justice if the requests have been submitted by the same body, pursuant to the same agreement, and regarding closely related legal questions.

The Principle of Non-Circumvention in Proceedings Instituted by Small Organizations

In theory, advisory proceedings do not enable states to bypass the consensual basis of jurisdiction in contentious proceedings. This principle of non-circumvention is arguably easier to safeguard in opinions relating to a common concern of the international community—such as in Nuclear Weapons (UNGA), or the prospective ITLOS opinions in COSIS—than those arising from a particular bilateral dispute, such as Wall. While ITLOS may consider the principle when assessing its own discretion to give or refuse an advisory opinion (particularly “if the question posed could directly influence the legality of climate-change related measures of a particular State or States”) [Tanaka, p. 9, citing Western Sahara, para 32], it “does not provide an exhaustive basis for explaining the discretionary power of a court to accept or decline a request for advisory opinion” [Barnes, p. 199].

A more novel and specific issue concerns the possible circumvention of the consent of a non-member state. The issue does not arise in ICJ advisory opinions requested by UNGA, since all UN Members are represented in that body. Nor has it clearly arisen in opinions of the ITLOS Seabed Disputes Chamber, which may be requested by the International Seabed Authority through a procedure explicitly set out in UNCLOS.

In SRFC, however, the requesting organization raised questions which were of general application to UNCLOS Contracting Parties, and which thus concerned the rights and obligations of interested flag states that had not participated in their framing or adoption. The Tribunal nevertheless found that this did not affect its competence to render an opinion [para 76], with Judge Cot expressing some concern that it should avoid construing its Statute in a manner which allows states to use bilateral or multilateral agreements to “seek to gain an advantage over third States” [para 9].

Application of the Principle of Non-Circumvention to COSIS

At face value, SRFC thus suggests a similar conclusion in COSIS, where a small organization has raised questions concerning the obligations of UNCLOS Contracting Parties that are not represented in the Commission. While the SRFC’s membership clearly had ‘skin in the game’ when asking ITLOS about coastal state obligations, however, the Commission’s membership does not include any of the states whose obligations and policies would be most significantly affected by a finding that UNCLOS governs GHG emissions as “pollution of the marine environment”.

Is this a legally relevant distinction—a doctrine of specially affected states in advisory proceedings? Related objections concerning locus standi, incidental jurisdiction, and the Monetary Gold principle have not clearly surfaced in advisory proceedings. Nor are objections based on lex specialis exceptions to compulsory jurisdiction in contentious cases, such as Article 298(1)(a) of UNCLOS, clearly applicable to advisory proceedings.

Yet ITLOS is itself at the blurring front lines between advisory opinions and declaratory judgments. As summarized in this blog, the Tribunal found in its 2021 Mauritius v. Maldives judgment [para 243] that the ICJ’s Chagos advisory opinion had resolved questions of sovereignty with effectively res judicata force that was opposable to the Maldives.

If the policies of small island developing states (SIDS) are unlikely to be affected by clarified obligations to protect the marine environment from GHG emissions, one might further query: does posing this threshold question to ITLOS contribute to the “implementation […] of international law concerning climate change”, as set out in Article 2(1) of the Agreement?

In our view, however, such concerns do not support challenges to the Tribunal’s competence in the COSIS proceedings. Firstly, according to the principle of common but differentiated responsibilities, all states (however small) have obligations to implement regarding climate change. Indeed, some issues which ITLOS may yet consider—such as those regarding the consequences of sea level rise for coastal baselines and maritime entitlements—concern the rights and obligations of SIDS to an obvious, existential degree.

More fundamentally, as observed in Peace Treaties, an advisory opinion “is given not to the States, but to the organ which is entitled to request it” [p. 71]. An opinion clarifying concepts in the law of the sea and related regimes would undoubtedly serve this particular organization’s mandate to “promote and contribute to the definition […] of rules and principles of international law concerning climate change”.


As Judge Crawford observed in the Marshall Islands cases, “a multilateral disagreement can crystallize for adjacent purposes as a series of individual disputes” [para 22]. In this manner, climate change gives rise to multilateral disagreements and a matrix of bilateral disputes. It may thus be framed for the purposes of advisory as well as contentious proceedings. While issues of consent to proceedings may arise in both settings, they do not control the discretion of ITLOS to accept or decline to render an advisory opinion.

The questions which the Commission has submitted to ITLOS appear to comply with the terms of its Agreement, and to be anchored in rights and obligations under UNCLOS. They reflect our planet’s shared interests in the ocean-climate nexus, as well as the urgency of the 2022 Lisbon Declaration of the UN Ocean Conference. They will also likely yield answers which ripple from Hamburg to The Hague, informing the ICJ’s treatment of references in the draft UNGA resolution to UNCLOS and the duty to protect and preserve the marine environment.

Therefore, rather than raise the spectre of “compelling reasons” to decline to render an advisory opinion (as hypothesized in SRFC) [para 71], the COSIS proceedings provide compelling reasons for the Tribunal to contribute its expertise and efficiency to the resolution of these questions. The Commission’s unique mandate may thus prove to be quite a nimble innovation, arriving not a moment too soon.

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