INTERNATIONAL COURT OF JUSTICE
OBLIGATIONS OF STATES IN RESPECT OF CLIMATE CHANGE
(REQUEST FOR AN ADVISORY OPINION)
URUGUAY
ANSWERS TO QUESTIONS PUT BY JUDGES
CLEVELAND, TLADI, AURESCU AND CHARLESWORTH
20 December 2024
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I. Question put by Judge Cleveland
1. “During these proceedings, a number of participants have referred to the production of
fossil fuels in the context of climate change, including with respect to subsidies. In your
view, what are the specific obligations under international law of States within whose
jurisdiction fossil fuels are produced to ensure protection of the climate system and other
parts of the environment from anthropogenic emissions of greenhouse gases, if any?”
Answer to question put by Judge Cleveland:
2. In its written submissions, Uruguay did not specifically address the particular issue of
fossil fuels in the context of climate change. However, Uruguay considers that any action
carried out by a State on the matter shall be consistent with its obligations under
international law to ensure the protection of the climate system and other parts of the
environment, including the duty to prevent serious or irreversible environmental damage
even in the absence of full scientific certainty, in accordance with the precautionary
principle, and the duty to comply with their existing obligations to mitigate GHG
emissions. Uruguay respectfully refers, in this regard, to its previous submissions.
3. Uruguay further notes that, as explained in its submissions, in specific circumstances,
legal consequences may also arise with respect to harm caused to the climate system or
other parts of the environment as a result of acts or omissions not prohibited by
international law.
II. Question put by Judge Tladi
4. “In their written and oral pleadings, participants have generally engaged in an
interpretation of the various paragraphs of Article 4 of the Paris Agreement. Many
participants have, on the basis of this interpretation, come to the conclusion that, to the
extent that Article 4 imposes any obligations in respect of Nationally Determined
Contributions, these are procedural obligations. Participants coming to this conclusion
have, in general, relied on the ordinary meaning of the words, context and sometimes
some elements in Article 31 (3) of the Vienna Convention on the Law of Treaties. I would
like to know from the participants whether, according to them, “the object and purpose”
of the Paris Agreement, and the object and purpose of the climate change treaty
framework in general, has any effect on this interpretation and if so, what effect does it
have?”
Answer to question put by Judge Tladi:
5. As previously stated by Uruguay in its two written submissions to the Court, Article 4 of
the Paris Agreement establishes a series of binding commitments for States.
6. Particularly, the Paris Agreement provides that States have an obligation to determine
and communicate their Nationally Determined Contributions (“NDCs”) and to adopt
domestic mitigation measures aimed at achieving the objectives established therein, as
unambiguously provided by its Article 4.2:
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Each Party shall prepare, communicate and maintain successive nationally determined
contributions that it intends to achieve. Parties shall pursue domestic mitigation
measures, with the aim of achieving the objectives of such contributions.1
7. Article 4.2 of the Paris Agreement does not prescribe the specific measures that States
should include in their NDCs, nor does it bind States to achieving a specific result as
regards the objectives set out in their NDCs.2 However, this does not mean that States are
free to choose whether to comply with their NDCs. To the contrary, NDCs must be
implemented in good faith, and in accordance with the duty of care applicable under the
standard of due diligence under international law.
8. In that regard, Uruguay reaffirms that “every treaty in force is binding upon the parties to
it and must be performed by them in good faith”,3 as enshrined in Article 26 of the Vienna
Convention on the Law of Treaties (“VCLT”), comprising a fundamental principle of
international law. This was also explained by the Court in the case concerning the
Gabčikovo-Nagymaros Project, where the Court stated that the principle of pacta sunt
servanda implies that “it is the purpose of the Treaty, and the intentions of the parties in
concluding it, which should prevail over its literal application”.4 Thus, the Court held that
the principle of good faith “obliges the Parties to apply [treaties] in a reasonable way and
in such a manner that its purpose can be realized”.5 Uruguay considers that the States’
obligations in connection with the climate system and other parts of the environment —
in particular under the various climate-related treaties which the Court has been called by
the General Assembly to have in “particular regard” when rendering its advisory
opinion—should be assessed in light of this fundamental principle of law.
9. Furthermore, Uruguay reiterates that customary obligations concerning the protection of
the environment have an erga omnes character, in that they are not obligations owed to
one particular State but to the international community of States as a whole, and that can
1 Conference of the Parties, Adoption of the Paris Agreement to the United Nations Framework
Convention on Climate Change (adopted 12 December 2015, entered into force 4 November 2016)
UN Doc. FCCC/CP/2015/10/Add.1 Decision 1/CP.21 (“Paris Agreement”), Article 4.2.
2 See Written Submission of the United States of America, ¶ 3.17 (“Although Parties have an
obligation to formulate, communicate, and maintain successive NDCs, the Paris Agreement
deliberately does not require Parties to achieve their NDCs”).
3 Vienna Convention on the Law of Treaties (1969), Article 26; See also, Jean Salomon, “Volume I,
Part III Observance, Application and Interpretation of Treaties, s.1 Observance of Treaties, Art.26
1969 Vienna Convention”, in Olivier Corten, Pierre Klein (eds), The Vienna Convention on the Law
of Treaties (Oxford University Press, 2011), ¶ 6.
4 Gabčikovo-Nagymaros Project (Hungary v. Slovakia), Judgment, I.C.J. Reports 1997, ¶ 142.
5 Gabčikovo-Nagymaros Project (Hungary v. Slovakia), Judgment, I.C.J. Reports 1997, ¶ 142.
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be enforced by any State on behalf of that community.6 This erga omnes character arises
from the shared nature of the natural resources potentially affected by State actions that
are harmful to the environment. Against this background, Uruguay respectfully
understands that, in accordance with the entire body of international law, States have
obligations vis-à-vis other States to ensure the protection of the climate system and other
parts of the environment.
10. Uruguay shares the view that, theoretically, the existence of any conflicts between the
UNFCCC and the Paris Agreement should be resolved in favour of the application of the
Paris Agreement, following Article 30 of the VCLT. However, Uruguay does not share the
view that this entails that the Paris Agreement should be afforded more weight in the
construction of the UN climate change regime. Rather, Uruguay submits that the UNFCCC
and the Paris Agreement should be interpreted and applied jointly.7 This is compatible
with the UNFCCC’s role as a framework agreement, which provides the general principles
and obligations that subsequent agreements are meant to further specify, and further
demonstrated by the provision in the Paris Agreement of measures to “enhanc[e] the
implementation of the Convention”.8 The existence of any conflicts or contradictions
between the UNFCCC and the Paris Agreement is unlikely and, were it to potentially exist,
a harmonizing interpretation should be preferred.
III. Question put by Judge Aurescu
11. “Some participants have argued, during the written and/or oral stages of the proceedings,
that there exists the right to a clean, healthy and sustainable environment in international
law. Could you please develop what is, in your view, the legal content of this right and its
relation with the other human rights which you consider relevant for this advisory
opinion?”
Answer to question put by Judge Aurescu:
12. Uruguay respectfully agrees with the view that the existence of a human right to a clean,
healthy and sustainable environment is undeniable as a matter of international law.9
6 Patricia Birnie, Alan Boyle, and Catherine Redgwell, International Law and the Environment (3rd ed.,
Oxford University Press, 2009), p. 131; International Law Commission, Draft Articles on
Responsibility of States for Internationally Wrongful Acts (2001) Article 48 (“Article 48. Invocation
of responsibility by a State other than an injured State 1. Any State other than an injured State is
entitled to invoke the responsibility of another State in accordance with paragraph 2 if: […] (b) the
obligation breached is owed to the international community as a whole.”)
7 See Written Submission of the French Republic, ¶ 13.
8 See Paris Agreement, Article 2. See also Written Submission of the Republic of South Africa, ¶ 36.
9 See Written Submission of the Argentine Republic, ¶ 38; Written Submission of Barbados, ¶ 165;
Written Submission of the Republic of Colombia, ¶¶ 2.3, 3.67; Written Submission of the Kingdom
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13. Particularly noteworthy is the leading role that the Inter-American system has played in
this area, both in terms of standards and advisory opinions. For instance, the Protocol of
San Salvador to the American Convention on Human Rights expressly recognizes in its
Article 11 that “everyone has a right to live in a healthy environment and to have access
to basic public services”, and that the State Parties shall “promote the protection,
preservation, and improvement of the environment.”10
14. More recently, the “Regional Agreement on Access to Information, Public Participation
and Justice in Environmental Matters in Latin America and the Caribbean”, adopted in
Escazú, Costa Rica, on 4 March 201811, provides in its Article 1:
The objective of the present Agreement is to guarantee the full and effective
implementation in Latin America and the Caribbean of the rights of access to
environmental information, public participation in the environmental decision-making
process and access to justice in environmental matters, and the creation and
strengthening of capacities and cooperation, contributing to the protection of the right
of every person of present and future generations to live in a healthy environment and
to sustainable development.12
15. Other regional instruments that expressly recognize the right to a healthy environment
include the American Declaration on the Rights of Indigenous Peoples,13 the African
Charter on Human and Peoples’ Rights,14 the ASEAN Human Rights Declaration,15 the Arab
Charter on Human Rights16 and the Aarhus Convention.17 These instruments show that
of Spain, Section E, ¶ 15; Written Submission of the Netherlands, ¶ 3.34. For different views on
this matter, see Written Submission of the People’s Republic of China, ¶¶ 115-119; Written
Submission of the Kingdom of Tonga, ¶ 244.
10 Additional Protocol to the American Convention on Human Rights in the Area of Economic, Social
and Cultural Rights (Protocol of San Salvador) (entered into force 16 November 1999) OAS Treaty
Series No 69 (1988), Article 11. See also Inter-American Court of Human Rights, Advisory Opinion
OC-23/17 of 15 November 2017, ¶¶ 56 et seq.
11 Regional Agreement on Access to Information, Public Participation and Justice in Environmental
Matters in Latin America and the Caribbean (“Escazú Agreement”). To date, the Escazú Agreement
has been signed to date by 24 Latin American and Caribbean States.
12 Escazú Agreement, Article 1.
13 American Declaration on the Rights of Indigenous Peoples, Article 19.
14 African Charter on Human and Peoples’ Rights (adopted 27 June 1981, entered into force 21
October 1986) (1982) 21 ILM 58 (“African Charter on Human and Peoples’ Rights”), Article 24.
15 Association of Southeast Asian Nations, ASEAN Human Rights Declaration (signed 19 November
2012), Article 28(f).
16 League of Arab States, Arab Charter on Human Rights (adopted 22 May 2004, entry into force 15
March 2008), 12 International Human Rights Reports 893, Article 38.
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the express recognition of the right to a clean, healthy and sustainable environment in
international treaties already exists in several regional treaties worldwide, which trend
will likely continue in the coming years.
16. Additionally, at an international level, both the United Nations Human Rights Council and
the United Nations General Assembly have recently adopted resolutions that are relevant
to this issue.
17. Notably, the Human Rights Council Resolution 48/13 of 8 October 2021, entitled “The
human right to a clean, healthy and sustainable environment”, recognized “the right to a
clean, healthy and sustainable environment as a human right that is important for the
enjoyment of human rights.” In addition, Resolution 48/13 affirmed that “the promotion
of the human right to a clean, healthy and sustainable environment requires the full
implementation of the multilateral environmental agreements under the principles of
international environmental law”, and encouraged States to “adopt policies for the
enjoyment of the right to a clean, healthy and sustainable environment as appropriate,
including with respect to biodiversity and ecosystems”.18
18. More recently, the Resolution No. 76/300 of the United Nations General Assembly, of 28
July 2022, recognizes “the right to a clean, healthy and sustainable environment as a
human right” which is “related to other rights and existing international law”. It also
provides that the promotion of this right “requires the full implementation of the
multilateral environmental agreements under the principles of international
environmental law” and calls upon actors to “enhance international cooperation,
strengthen capacity-building and continue to share good practices in order to scale up
efforts to ensure a clean, healthy and sustainable environment for all.”19
19. Therefore, Uruguay states that the existence of a human right to a clean environment
under international law has been sufficiently established, contrary to certain views
advanced in these proceedings.
20. Furthermore, beyond the undeniable existence of the human right to a clean
environment under international law, Uruguay reiterates that GHG emissions and their
impact on the climate system may adversely affect the enjoyment of other numerous
human rights. As noted by Spain in its written submission:
[T]he human right to a clean, healthy and sustainable environment offers greater
coherence to the human rights system. Due to its cohesive nature, the human right to a
clean, healthy and sustainable environment is pertinent to several categories of rights:
17 United Nations Economic Commission for Europe, Convention on Access to Information, Public
Participation in Decision-making and Access to Justice in Environmental Matters (adopted 25 June
1998, entry into force 30 October 2001) 2161 UNTS 447, Preamble.
18 Human Rights Council Resolution 48/13 of 8 October 2021.
19 Resolution No. 76/300 of the United Nations General Assembly, of 28 July 2022.
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as a right to life, it imposes positive obligations on States; as an economic and social
right, it promotes progress that should be much more inclusive; and finally as a
collective and solidary right it protects the environment, while its democratic nature
allows the ecosystem protection and management model to be decided by and for
all.20
21. Based on the foregoing, Uruguay reiterates its position that, even in the absence of a right
to a clean, healthy and sustainable environment under international law, States are under
the obligation to adopt mitigation and adaptation measures to protect the climate system
and other parts of the environment from the deleterious effects of GHG emissions under
their commitments to guarantee other human rights, including the right to life, the right
to health, and the right to culture, as well as States’ commitments as regards gender
equality.
IV. Question put by Judge Charlesworth
22. “In your understanding, what is the significance of the declarations made by some States
on becoming parties to the UNFCCC and the Paris Agreement to the effect that no
provision in these agreements may be interpreted as derogating from principles of general
international law or any claims or rights concerning compensation or liability due to the
adverse effects of climate change?”
Answer to question put by Judge Charlesworth:
23. First of all, Uruguay reiterates that the prevention principle arising from customary
international law is not displaced by States’ obligations under the UNFCCC, the Paris
Agreement, UNCLOS and other treaties relevant to climate change. To the contrary, the
duty to prevent transboundary harm is a standalone obligation under customary
international law, while the standard of due diligence required under the prevention
principle should be applied to provide greater clarity as to the specific conduct that may
be expected from States in compliance with their undertakings.
24. When it comes to compensation or liability, it is trite that every internationally wrongful
act of a State entails the international responsibility of that State.21 In general, the
international responsibility of a State involves a series of legal consequences, including:22
20 Written Submission of the Kingdom of Spain, ¶ 12.
21 See, e.g., International Law Commission, Articles on Responsibility of States for Internationally
Wrongful Acts (2001) Article 1; S.S. “Wimbledon”, PCIJ, Series A, No. 1, Judgment, August 1923,
p. 30; Phosphates in Morocco, PCIJ, Series A/B, No. 74, Judgment on Preliminary Objections, 14
June 1938, p. 28; Gabčikovo-Nagymaros Project (Hungary v. Slovakia), Judgment, I.C.J. Reports
1997, ¶ 47.
22 In accordance with the International Law Commission’s Draft Articles on Responsibility of States for
Internationally Wrongful Acts (2001) specific legal consequences may arise from “special rules of
international law”.
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obligation to cease the wrongful conduct,23 obligation to offer appropriate assurances
and guarantees of non-repetition,24 and obligation to make full reparation for the injury
caused by the internationally wrongful act25 by restitution,26 compensation27 or
satisfaction.28
25. As set out in Uruguay’s written submissions, States have the obligation to ensure the
protection of the climate system and other parts of the environment. Accordingly, any
breach of said obligations by a State would give rise to its international responsibility and
the subsequent obligation to make full reparation.29
26. In the case of significant harm to the climate system and other parts of the environment,
while there is “scientific consensus” that “anthropogenic emissions of greenhouses gases
are unequivocally the dominant cause of the global warming observed since the mid-20th
century, that human-induced climate change, including more frequent and intense
extreme events, has caused widespread adverse impacts and related losses and damages
to nature and people, beyond natural climate variability, and that across sectors and
regions the most vulnerable people and systems are observed to be disproportionately
affected”,30 due to the diffuse nature of the harm itself and the several historical and
23 See International Law Commission, Draft Articles on Responsibility of States for Internationally
Wrongful Acts (2001), Article 30(a).
24 See Articles on Responsibility of States for Internationally Wrongful Acts, Article 30(b).
25 Factory at Chorzów, PCIJ, Series A, No. 9, Judgment on Jurisdiction, 26 July 1927, p. 21. See also,
e.g., Factory at Chorzów, PCIJ, Series A, No. 17, Judgment on Merits, 13 September 1928, p. 29.
26 See International Law Commission, Articles on Responsibility of States for Internationally Wrongful
Acts (2001), Article 35.
27 See International Law Commission, Articles on Responsibility of States for Internationally Wrongful
Acts (2001), Article 36.
28 See International Law Commission, Articles on Responsibility of States for Internationally Wrongful
Acts (2001), Article 37.
29 The obligation to compensate may also arise from a rule of international law providing for strict
responsibility based on harm or injury only. See, e.g., Resolution by the Institut de Droit
International on “Responsibility and Liability under International Law for Environmental Damage”,
Session of Strasbourg, 4 September 1997. See also The Environment and Human Rights, Advisory
Opinion OC-23/17, Inter-American Court of Human Rights, 15 November 2017, ¶ 103.
30 UN General Assembly, Resolution 77/276, Request for an Advisory Opinion of the International
Court of Justice on the Obligations of States in Respect of Climate Change (29 March 2023). See
also above, Section II.A.
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concurrent causes, including the acts and omissions of several States, establishing a link
between the conduct of a specific State and a specific harm is particularly challenging.31
27. However, Uruguay respectfully reiterates its position, as set out in its written and oral
statements, that any alleged difficulties to establish a causal link between a State’s
conduct and certain environmental harm do not preclude, in principle, the legal
consequences for the States that have caused—or contributed to cause—the significant
harm.
31 See, in this regard, International Law Commission, Draft Articles on Responsibility of States for
Internationally Wrongful Acts (2001), Articles 14 and 15.
Written reply of Uruguay to the questions put by Judges Cleveland, Tladi, Aurescu and Charlesworth at the end of the hearing held on 13 December 2024