Symposium on Advisory Opinion AO-32/25 on the Climate Emergency and Human Rights: Finally Some Clarification on the Legal Effects of Advisory Opinions?

[Eduardo Cavalcanti de Mello Filho is an MPhil candidate at the Faculty of Laws, University College London. This post was written while the author was a research associate at the Centre for International Law, National University of Singapore.]

In this post, I claim that Advisory Opinion 32/25 (AO-32/25 or Opinion) of the Inter-American Court of Human Rights (Court) reshapes the way we should think about the legal effects of advisory opinions in international law. The Court did two things that deserve particular attention. First, it extended the reach of its pronouncement to all Member States of the Organization of American States (OAS), including the United States (US) and Canada, though they are not parties to the 1969 American Convention on Human Rights (ACHR), which established the Court’s jurisdiction. Second, it held that American States, in implementing the relevant human rights rules, must “consider integrally” the interpretation set out in the Opinion (para. 41).

Across five sections, this post examines the Opinion’s geographical reach and the obligation to “consider integrally” the Court’s interpretation in the Opinion. My specific proposition explains this obligation by arguing that the Opinion’s legal weight should not be measured by its formal non-binding nature. Rather, I argue that the Opinion constitutes a privileged material source of law that should play a fundamental role in the creation and interpretation of international human rights. As such, American States must engage with it while interpreting or applying binding human rights obligations.

The first and second sections cover the Opinion’s reach to OAS States and  States beyond America. The third to fifth sections address the Opinion as a material source of law, situating OAS States’ obligation to consider it integrally. Concluding remarks follow.

Why the Opinion Reaches All OAS States

The request for Advisory Opinion 32, made by Colombia and Chile, asked the Court to interpret the ACHR and the 1988 Protocol of San Salvador. The Convention is currently in force for 25 of the 35 OAS member states. Ten members, including the US, Canada, and most English-speaking Caribbean countries, have not ratified it. Yet the Court made clear that its pronouncement reaches the full membership of the OAS (para. 41), which is not entirely unprecedented (e.g., OC-18/03, para. 56-60).

In the Opinion, the Court started by reaffirming that human rights obligations set forth in the 1948 OAS Charter, such as in Article 3(l), are fleshed out in the 1948 American Declaration on Human Rights (para. 40), while adding that “the rights whose scope will be determined in this advisory opinion are likewise enshrined in the American Declaration” (para. 39). This made explicit a basic aspect of the Court and the Commission’s practice: to mention the provisions in relevant inter-American (and sometimes global) human rights instruments having to do with the right it is interpreting in each specific case. For example, in the Opinion itself, the Court referred to Article 1 of the American Declaration while addressing the right to life, analyzed as found in Article 4 of the ACHR (para. 393).

This attention to sources of international human rights law beyond the Convention, object of the Chilean-Colombian request, is due to the Court’s specific competence under Article 64 of the ACHR to issue advisory opinions, which also covers “other treaties concerning the protection of human rights in the American States.” The Court reaffirmed (para. 40), “in the exercise of its advisory jurisdiction, the Court must contribute to the recognition and development of the fundamental human rights by OAS Member States.”

This approach reinforces coherence in what the Opinion calls the “inter-American public order” (para. 22). This notion is further developed below, as it focuses on the inter-American human rights system as a corpus juris autonomous from the domestic legal system. With respect to the US and Canada in particular, they are still subject to the jurisdiction of the Inter-American Commission on Human Rights, provided for in the OAS Charter Article 106, but governed by the ACHR. Though it does not have the power to issue binding decisions, the Commission is mandated to hear individual submissions and, in that regard, to make recommendations to OAS Member States, besides other activities related to the monitoring and promotion of human rights in each country.  It is expected that the Commission will defer to Opinion 32 while interpreting the American Declaration. Indeed, already in its Resolution 3/21 Climate Emergency: Scope of Inter-American Human Rights Obligations (p. 5), the Commission relied on the Court’s Opinion 23/17 to elaborate on the right to a healthy environment.

Beyond the Americas?

The Court ruled on basic human rights, including the peremptory nature of the “prohibitions arising from the obligation to preserve our ecosystem” (para. 291). These are considerations of a general nature that cannot be limited to the Americas under the guise of the Court and the Convention being “Inter-American.”  Climate change and the Court’s core reasoning in its respect are global. Hence, all States in the world, bound by global human rights treaties or customary law, are impacted by the Court’s Opinion.

Notwithstanding the above, the Court did not extend the obligation to “consider integrally” its interpretation of human rights law to States beyond the Americas. I understand that this is wise not only because the Court is an OAS body but also because Opinion 32, as a material source of law, is arguably less compelling outside the American continent. In the next sections, as I address the compellingness of Opinion 32 as a material source of law, I entertain its resonance beyond the Americas.

Opinion 32 and Material Sources of Law

Formally, advisory opinions are not binding on states (p. 304), be they delivered by the International Court of Justice, the International Tribunal for the Law of the Sea, or by the Inter-American Court. (Some authors, notably Ledesma (p. 989-994), have understood IACtHR ones to be binding.) Yet courts themselves often describe advisory opinions as having legal effects. ITLOS stated in Mauritius/Maldives that ICJ’s advisory opinion on Chagos had “legal effects” (paras. 205–206). In Opinion 15, the IACtHR famously declared that its opinions have “undeniable legal effects” (para. 26).

How can a text that is formally non-binding nonetheless be described as having legal effects? The answer lies in the distinction between formal and material sources of international law (see, more generally, Fitzmaurice).

Formal sources, such as treaties, customary international law, and general principles of law, are recognised as law-making processes. They are sources of legal obligation by virtue of their form. For example, there is a principle of international law called pacta sunt servanda that is generally accepted and, in any case, assumed. On the basis of this principle, valid treaties give rise to binding legal obligations. Similar rationales apply to customary international law and general principles of law. States and legal operators must apply them.

Material sources, by contrast, supply the substance of law without themselves creating formal obligations, and therefore need not be followed. Most law textbooks refer to material sources as social, economic, political, moral, historical, and cultural influences shaping the law. They may inspire formal general legislative processes and influence the interpretation of existing obligations. Significantly, following post-positivist jurisprudence, interpretation, too, has an intrinsic law-making nature, as it may concretely determine the existence, reach, and depth of general legal obligations.

(Non-binding) judicial decisions, scholarly writings, and resolutions are often placed in this category insofar as they capture those influences, present persuasive reasonings, and offer guidance orienting law-making processes. A famous example of a decision decisively orienting the interpretation of existing law and inspiring treaty-making is the ICJ judgment in the 1951 Fisheries case, where it found that Norway’s straight baselines were in accordance with international law.

Formal sources may be prescriptive in great detail, in which case there is no need to resort to material sources. But this is not the case in international human rights law. With exceptions, human rights instruments typically stipulate general rights, and the applicable treaty interpretation rules are hardly constraining. If human rights obligations are to be interpreted and applied to be effective at all, especially as a “living instrument,” some flesh must be put in their bones (see Conc. Op. Judge Trindade, OC-16/99, paras 2-15).

Absent systems for incrementing these formal sources, such as binding precedents or a facilitated amendment procedure, this flesh is usually furnished by material sources of law in legal interpretation. According to Cançado Trindade (p. 145), the material source par excellence in international law is the “universal juridical conscience,” shaped not by the whims of States (relevant for formal sources) but by the common conscience of human beings. 

Thus, the observance of formal obligations, if interpreted correctly, also requires the observance of the content in material sources. It would be cynical, thus not in good faith, for a State to claim to observe formal sources in a hypothetically isolated manner, raising the non-binding nature of material sources. 

A classic example in the context of climate change concerns the right to life and the Court’s interpretation of its environmental dimension (do note that the Court also affirmed the autonomy of the right to a healthy environment, para. 274). In such a case, an American State could not, in good faith, justify environmental degradation by asserting that it is bound only by the formal right to life, while ignoring the Court’s authoritative interpretation of its environmental content.

The argument developed below is that the Opinions of the IACtHR authoritatively capture and give concrete shape to this “universal juridical conscience,” particularly as experienced in the “inter-American public order” (para. 22).

A Privileged Material Source

Not all material sources may equally influence the creation and interpretation of binding legal obligations. Described by Fitzmaurice (p. 75-76) as undoubtedly material sources but also as “quasi-formal sources”,  “some kinds of decisions, once given, are almost certain, or intrinsically likely to be followed” and even if not followed, they cannot be ignored, as opposed to, say, the opinion of eminent jurists. He observed that this is in the nature and day-to-day of legal practice. Opinion 32 is certainly one of these decisions.

This assertion is evident if one considers the specifics of international human rights law, where States’ obligations are primarily owed not to other States but to human beings under their jurisdiction or control. In this sense, the (inter-American) human rights system is an autonomous order, with concepts independent from States’ domestic legal concepts (Sep. Op. Judge Trindade, Caesar v. Trinidad and Tobago, 2005, paras. 7-10). Indeed, a regional human rights protection system would be of no avail if States were free to determine its basic concepts on the basis of their own domestic law.  Rather, their domestic law advances either compliance or a violation of inter-American human rights obligations, whereas State practice might be more decisive in informing the obligations held by and owed to States.

In this autonomous order, the Inter-American Court is in a privileged position. It is, after all, the “ultimate interpreter of the convention” (OC-20/09, para. 18). Its pronouncements are authoritative within the inter-American system, where 25 states face potential contentious litigation and all 35 states fall under the monitoring of the Commission. 

That the Opinion is a privileged (material) source of law is further attested to by the OAS Permanent Council, as it “urge[d] Member States to fully integrate human‑rights considerations into all climate‑related policies and actions, as established in Advisory Opinion No. 32/25 of the Inter‑American Court of Human Rights” (CP/DEC. 86 (2559/25).

This is congruent with the Court’s correct choice of words in Opinion 32: All OAS member states must “consider integrally” its interpretation (para. 41).

What Does It Mean to “Consider Integrally”?

The phrase deserves careful attention. It does not mean that states must conform to the advisory opinion in the same way they must comply with a binding specific judgment. Indeed, this judicial output is, of course, general and does not provide for details pertaining to the specific situation of each State concerned, which in any case preserves its margin of appreciation.

But “consider integrally” is stronger than merely “taking into account.” It suggests that American States cannot cherry-pick convenient parts of the Opinion while ignoring others. An example could be a State that agrees with the Court in principle but turns a blind eye to the logical consequences of the Opinion, including the Court’s statement that “mitigation strategies should necessarily include measures to advance in progressive reduction of GHG emissions from fossil fuels, agriculture, livestock, deforestation, and other land use” (para. 337). American States must treat the Court’s interpretation as a whole and give it serious weight when implementing their human rights obligations. This is particularly important given the autonomy of the inter-American human rights system from domestic legal concepts.

The IACtHR was also right to limit this obligation to American States, and not only because of its specific OAS-centered competence. Opinion 32 indeed remains a fundamental material source that certainly cannot be ignored regarding compliance with general human rights obligations. However, one must note that the compellingness of material sources is intrinsically bound to their perceived legitimacy. Beyond the Court’s recognized legal expertise, its legitimacy is naturally less felt among extra-American States, which do not have the Court as the “ultimate interpreter” of their core human rights obligations.

Conclusion

Opinion 32 is not binding, yet it carries legal effects, which are that all American States must consider it integrally while interpreting and applying climate change-related human rights rules. This assertion is only paradoxical to those believing that legal effects end with formal sources. Following Cançado Trindade’s doctrine, if binding obligations are to be interpreted and applied effectively and in good faith, material sources must be considered, particularly in human rights law. 

As demonstrated, this understanding is even more persuasive in the case of a regional human rights protection system, which is autonomous from domestic legal systems and has the Court as the “ultimate interpreter” of human rights instruments in the region. Given the Court’s contentious jurisdiction and the Commission’s competence, it is likely that Opinion 32’s legal effects will soon prove actual.