Applier, Interpreter, and Judicial Codifier: the Three Climate Advisory Opinions, Sustainable Development, and International Judicial Legitimacy

Raúl Zeyi Huang

doi:10.21697/2026.15.1.05

Published: 2026-06-26

Vol. 15 No. 1 (2026)

Applier, Interpreter, and Judicial Codifier: the Three Climate Advisory Opinions, Sustainable Development, and International Judicial Legitimacy

Raúl Zeyi Huang

Polish Review of International and European Law

Section: Articles

https://doi.org/10.21697/2026.15.1.05

Abstract

The International Tribunal for the Law of the Sea, the Inter-American Court of Human Rights and the International Court of Justice have recently issued three landmark climate advisory opinions. Amidst the long-standing ambiguity of sustainable development in international law, this paper analyzes how the advisory opinions contributed to its clarification and development and proposes a political explanation for their differences. As a treaty applier, the Tribunal was the most conservative in limiting its engagement to a textual interpretation of sustainability provisions in the Framework Convention. As a treaty interpreter, the Inter-American Court actively embraced sustainable development in answering both scientific and legal dimensions of the question presented. As a judicial codifier of international law, the World Court carefully identified shared legal consensus in the international community of States, while its reservation in climate mitigation and adaptation was criticized in Judge Xue’s Separate Opinion. Based on Professor Jorge Viñuales’s theory, after the present Advisory Opinions, sustainability remains a ‘normative concept’ in general international law, which supplies conceptual materials for legal and policy instrument and assists clarification of States’ obligations; however, within the regional system of inter-American human rights, the principle has become a fully entitled legal norm as an independent source of States’ obligation that is justiciable. Beyond the permanent debate over whether the advisory opinions have correctly applied law, a proposed political explanation, termed ‘international judicial relay’, reveals how the three bodies collaborate by playing to their respective strengths to contribute to the concept’s development at different stages, so that they earn instead of lose legitimacy. The relay begun before the Advisory Opinions, and will continue thereafter, that sustainability will be increasingly invoked in future advisory and contentious proceedings specific to trade and investment, and even private commercial disputes applying international law.

Keywords:

Sustainable Development, Climate Change, Advisory Opinion, International Courts and Tribunals, Judicial Politics

Download files

PDF

Citation rules

Huang, R. Z. (2026). Applier, Interpreter, and Judicial Codifier: the Three Climate Advisory Opinions, Sustainable Development, and International Judicial Legitimacy. Polish Review of International and European Law, 15(1), 145–169. https://doi.org/10.21697/2026.15.1.05

Cited by / Share

Licence

This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.

References

Afzall, Jamil, and Ahmad, Ibrar. “The ITLOS Advisory Opinion on Climate Change and Marine Pollution: Some Reflections.” Environmental Policy and Law 55 (2025): 68–75.
Google Scholar

American Convention on Human Rights, 22 November 1969, 1144 U.N.T.S. 123.
Google Scholar

Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosn. & Herz. v. Serb. and Montenegro), Judgment, 2007 I.C.J. Rep. 43 (26 February).
Google Scholar

Arbitration Regarding the Iron Rhine (“Ijzeren Rijn”) Railway (Belgium/Netherlands), Award, R.I.A.A. XXVII 35 (24 May 2005).
Google Scholar

Atapattu, Sumudu. “From ‘Our Common Future’ to Sustainable Development Goals: Evolution of Sustainable Development under International Law.” Wisconsin International Law Journal 36, no. 2 (2019): 215–246.
Google Scholar

Bañuelos, Jorge Alejandro Carrillo, and Samuel, Susan Ann. “Judicial Convergence on Climate Change: The Advisory Opinions of the ICJ, the IACtHR, and the ITLOS.” In The ICJ’s Advisory Opinion on Climate Change, edited by Maria Antonia Tigre, Maxim Bönnemann and Antoine De Spiegeleir. Berlin: Verfassungsbooks, 2025.
Google Scholar

Barnes, Richard. “An Advisory Opinion on Climate Change Obligations under International Law: A Realistic Prospect?” Ocean Development and International Law 53, no. 2–3 (2022): 180–213.
Google Scholar

Bodansky, Daniel. “Advisory Opinions on Climate Change: Some Preliminary Questions.” Review of European, Comparative & International Environmental Law 32, no. 2 (2023): 185–192.
Google Scholar

Borràs-Pentinat, Susana. “The IACtHR Climate Emergency Advisory Opinion: A Legal Analysis of the State Obligations.” Environmental Policy and Law (online first) (2025).
Google Scholar

Boshoff, Elsabé, and Damtew, Samrawit Getaneh. “Can Africa Still Drill?: What the ICJ Climate Opinion Means for Oil and Gas Exploration in Africa.” In The ICJ’s Advisory Opinion on Climate Change, edited by Maria Antonia Tigre, Maxim Bönnemann and Antoine De Spiegeleir. Berlin: Verfassungsbooks, 2025.
Google Scholar

Charter of the United Nations, 26 June 1945, XV U.N.C.I.O. 355.
Google Scholar

Convention on Biological Diversity, 5 June 1992, 1760 U.N.T.S. 79.
Google Scholar

Cooperation Framework relating to the Subregional Action Program for the Sustainable Development of the American Gran Chaco (March 2009).
Google Scholar

Fisheries Jurisdiction (United Kingdom of Great Britain and Northern Ireland v. Iceland), Judgment, 1974 I.C.J. Rep. 3 (25 July).
Google Scholar

Foster, Caroline E. “The 2025 International Court of Justice Advisory Opinion on Obligations of States in respect of Climate Change.” International and Comparative Law Quarterly 74, no. 4 (2025): 775–809.
Google Scholar

G.A. Res. 77/276 (29 March 2023).
Google Scholar

Gabčíkovo-Nagymaros Project (Hungary/Slovakia), Judgment, 1997 I.C.J. Rep. 7 (25 September).
Google Scholar

Inter-American Democratic Charter, 11 September 2001, 40 ILM 1289.
Google Scholar

International Law Association, New Delhi Declaration of Principles of International Law Relating to Sustainable Development (6 April 2002).
Google Scholar

Koskenniemi, Martti. From Apology to Utopia: The Structure of International Legal Argument. Cambridge: Cambridge University Press, 2005.
Google Scholar

Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996 I.C.J. Rep. 226 (8 July).
Google Scholar

Lowe, Vaughan. “Sustainable Development and Unsustainable Arguments.” In International Law and Sustainable Development: Past Achievements and Future Challenges, edited by Alan Boyle and David Freestone. Oxford: Oxford University Press, 1999.
Google Scholar

Marrakesh Agreement Establishing the World Trade Organization, 15 April 1994, 1867 U.N.T.S. 154.
Google Scholar

Military and Paramilitary Activities in and Against Nicaragua (Nicar. v. U.S.), Judgment, 1986 I.C.J. Rep. 14 (27 June).
Google Scholar

Obligations of States in Respect of Climate Change, Advisory Opinion, 2025 I.C.J. (23 July).
Google Scholar

Odermatt, Jed. “What the Court Didn’t Say: The ICJ’s Climate Opinion and the Politics of Judicial Restraint.” In The ICJ’s Advisory Opinion on Climate Change, edited by Maria Antonia Tigre, Maxim Bönnemann and Antoine De Spiegeleir. Berlin: Verfassungsbooks, 2025.
Google Scholar

Prosecutor v. Duško Tadić, Decision on the Defense Motion for Interlocutory Appeal on Jurisdiction, Case No. IT-94-1-AR72 (2 October 1995).
Google Scholar

Prosecutor v. Jadranko Prlić et al., Appeals Judgment, Case No. IT-04-74-A (29 November 2017).
Google Scholar

Request for Advisory Opinion No. 001 of 2025: In the matter of a request by the Pan African Lawyers Union (PALU) for an Advisory Opinion on the obligations of States with respect to the climate change crisis, AfCtHPR (2 May 2025).
Google Scholar

Request for an Advisory Opinion on the Climate Emergency and Human Rights submitted to the Inter-American Court of Human Rights by the Republic of Colombia and the Republic of Chile (9 January 2023).
Google Scholar

Request for an Advisory Opinion submitted by the Commission of Small Island States on Climate Change and International Law, Advisory Opinion, 2024 I.T.L.O.S. (21 May).
Google Scholar

Request for an Advisory Opinion submitted by the Sub-Regional Fisheries Commission, Advisory Opinion, 2015 I.T.L.O.S. Rep. 4 (2 April).
Google Scholar

Request for an Advisory Opinion Submitted by the Sub-Regional Fisheries Commission, Advisory Opinion, 2015 I.T.L.O.S. Rep. 4 (2 April).
Google Scholar

Rio Declaration on Environment and Development, 14 June 1992, UN Doc. A/CONF.151/26 (Vol. I).
Google Scholar

Samuel, Susan Ann, and Bañuelos, Jorge Alejandro Carrillo. “The Role of Advisory Opinions in International Law in the Context of the Climate Crisis: The Dialogue between the ICJ, the ITLOS, the IACtHR, and the AfCtHPR.” In The Role of Advisory Opinions in International Law in the Context of the Climate Crisis, edited by Maria Antonia Tigre and Armando Rocha. Boston: Brill, 2025.
Google Scholar

Shany, Yuval. Assessing the Effectiveness of International Courts. Oxford: Oxford University Press, 2014.
Google Scholar

Statute of the International Court of Justice, 26 June 1945, 59 Stat. 1055, 33 U.N.T.S. 993.
Google Scholar

Statute of the International Law Commission, G.A. Res. 174 (II) (21 November 1947).
Google Scholar

Statute of the International Tribunal for the Law of the Sea, Annex VI to the United Nations Convention on the Law of the Sea, 10 December 1982, 1833 U.N.T.S. 561.
Google Scholar

The Climate Emergency and Human Rights (Interpretation and scope of Articles 1(1), 2, 4(1), 5(1), 8, 11(2), 13, 17(1), 19, 21, 22, 23, 25 and 26 of the American Convention on Human Rights; 1, 2, 3, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18 of the Additional Protocol to the American Convention on Human Rights in the Area of Economic, Social and Cultural Rights “Protocol of San Salvador,” and I, II, IV, V, VI, VII, VIII, XI, XII, XIII, XIV, XVI, XVIII, XX, XXIII, and XXVII, of the American Declaration of the Rights and Duties of Man), Advisory Opinion, 2025 I.A.Ct.H.R. AO-32/25, Series A No. 32 (29 May).
Google Scholar

Tigre, Maria Antonia, Bönnemann, Maxim, and De Spiegeleir, Antoine. “The ICJ’s Advisory Opinion on Climate Change: An Introduction.” In The ICJ’s Advisory Opinion on Climate Change, edited by Maria Antonia Tigre, Maxim Bönnemann and Antoine De Spiegeleir. Berlin: Verfassungsbooks, 2025.
Google Scholar

Tigre, Maria Antonia. “It Is (Finally) Time for an Advisory Opinion on Climate Change: Challenges and Opportunities on a Trio of Initiatives.” Charleston Law Review 17 (2024): 623–721.
Google Scholar

UN Human Rights Committee, General Comment No. 36 on Article 6: Right to Life, UN Doc. CCPR/C/GC/36 (30 October 2018).
Google Scholar

United Nations Convention on the Law of the Sea, 10 December 1982, 1833 U.N.T.S. 3.
Google Scholar

United Nations Framework Convention on Climate Change, 9 May 1992, 1771 U.N.T.S. 107.
Google Scholar

United Nations. “United Nations Convention on the Law of the Sea, Montego Bay, 10 December 1982.” United Nations Treaty Collection. Accessed May 24, 2026. https://treaties.un.org/pages/ViewDetailsIII.aspx?src=TREATY&mtdsg_no=XXI-6&chapter=21&Temp=mtdsg3&clang=_en.
Google Scholar

United Nations. “United Nations Framework Convention on Climate Change, New York, 9 May 1992.” United Nations Treaty Collection. Accessed May 24, 2026. https://treaties.un.org/pages/ViewDetailsIII.aspx?src=TREATY&mtdsg_no=XXVII-7&chapter=27&Temp=mtdsg3&clang=_en.
Google Scholar

United States — Import Prohibition of Certain Shrimp and Shrimp Products, Appellate Body Report, WTO Doc. WT/DS58/AB/R (12 October 1998).
Google Scholar

Vienna Convention on the Law of Treaties, 23 May 1969, 1155 U.N.T.S. 331.
Google Scholar

Viñuales, Jorge E. “Sustainable Development.” In The Oxford Handbook of International Environmental Law, edited by Lavanya Rajamani and Jacqueline Peel. Oxford: Oxford University Press, 2021.
Google Scholar

Wewerinke-Singh, “Harmonizing Sources, Hardening Duties.” In The ICJ’s Advisory Opinion on Climate Change, edited by Maria Antonia Tigre, Maxim Bönnemann and Antoine De Spiegeleir. Berlin: Verfassungsbooks, 2025.
Google Scholar

Wewerinke-Singh, Margaretha. “Harmonizing Sources, Hardening Duties: Inside the ICJ’s Advisory Opinion on Climate Change.” In The ICJ’s Advisory Opinion on Climate Change, edited by Maria Antonia Tigre, Maxim Bönnemann and Antoine De Spiegeleir. Berlin: Verfassungsbooks, 2025.
Google Scholar

World Commission on Environment and Development. Our Common Future. Oxford: Oxford University Press, 1987.
Google Scholar