Introduction
This post outlines how the right to a healthy environment is addressed in the advisory opinions of the Inter-American Court of Human Rights (IACtHR, available here) and the International Court of Justice (ICJ, available here).
This blog post is based on my contribution to a panel discussion on ‘The Future for Human Rights and the Environment within the Regional Human Rights Systems’. The panel was part of the NNHRR Working Group on Human Rights & the Climate Crisis workshop, titled ‘Developments on Human Rights and the Environment in the Global South’. The workshop was organized by Patricio Trincado Vera and Julián Suárez Bohórquez and took place at Leiden University College The Hague on 4 December 2025.
In what follows, I compare the two opinions across six key dimensions: (1) their understanding of the legal basis of the right; (2) whether they treat it as a self-standing and autonomous right, or instead as a derivative, dependent and ancillary right; (3) the extent to which they extend it to future generations; (4) the degree to which they recognize nature itself as a rights-holder; (5) whether they characterize it as a peremptory norm (jus cogens) and/or a source of erga omnes obligations; and (6) the conditions under which they consider it applicable to multinational corporations. These six dimensions capture the key elements that shape the legal significance of the right to a healthy environment: its legal foundation, normative status, scope, as well as its beneficiaries and duty-bearers. Comparing the advisory opinions along these six dimensions reveals not only how each court conceptualizes the right, but also the extent to which these advisory opinions contribute to its development as a right under international law.
This post’s focus is exclusively on the right to a healthy environment. For an all-encompassing analysis of the role of advisory opinions in international law in the context of the climate crisis, see the book by Maria Antonia Tigre and Armando Rocha. For a more comprehensive commentary of the ICJ’s Advisory Opinion on Climate Change, see the book edited by Maria Antonia Tigre, Maxim Bönnemann & Antoine De Spiegeleir.
1. Legal Basis
Article 11 of the Additional Protocol to the American Convention on Human Rights contains a human right to a healthy environment. It reads as follows:
- Everyone shall have the right to live in a healthy environment and to have access to basic public services.
- The States Parties shall promote the protection, preservation, and improvement of the environment.
Article 11 itself is not directly justiciable before the Inter-American Court of Human Rights through the individual petition system established by Article 19(6) of this Protocol. The legal basis of the human right to a healthy environment is therefore rather complex, as explained by the IACtHR itself in its Advisory Opinion of 29 May 2025 on the Climate Emergency and Human Rights (para. 270):
The Court has indicated that the right to a healthy environment is one of the rights protected by Article 26 of the American Convention, under the obligation of States to achieve the “integral development” of their people, which arises from Articles 30, 31, 33 and 34 of the OAS Charter. Regarding the content and scope of this right, the Court recalls that Article 11 of the Protocol of San Salvador stipulates that “[e]veryone shall have the right to live in a healthy environment and to have access to basic public services” and that State Parties “shall promote the protection, preservation, and improvement of the environment.”
In its Advisory Opinion of 23 July 2025 on Obligations of States in Respect of Climate Change, the ICJ did not find a universally applicable treaty to rely on. Instead, it noted that several regional human rights instruments recognise, in variously worded provisions, the right to a healthy environment. It referred to the African Charter on Human and Peoples’ Rights, the Arab Charter on Human Rights, and the Additional Protocol to the American Convention on Human Rights which was just cited above. Interestingly, the ICJ did not refer to the European Convention on Human Rights as a source recognising a right to a healthy environment. Only one case of the European Court of Human Rights, the KlimaSeniorinnen judgment of 9 April 2024, is (twice) referred to, though only as part of a long list of cases (see paragraphs 144 and 385 of the opinion).
It is worth noting that both courts relied on the UN Human Rights Council and UN General Assembly resolutions recognising the right to a healthy environment, adopted 8 October 2021 and 28 July 2022, respectively. For the ICJ, these resolutions were particularly important as indicators of emerging international consensus and potentially of opinio juris, given the absence of a universally binding treaty recognizing the right to a healthy environment.
2. Is it a Self-Standing and Autonomous Right or is a Healthy Environment a Precondition for the Enjoyment of Many Conventional Human Rights?
The IACtHR recognized the right to a healthy environment as an autonomous fundamental right (paragraphs 272-274 of its opinion).
The ICJ first observed that ‘the effective enjoyment of a number of human rights cannot be fully realized if those who hold them are unable to live in a clean, healthy and sustainable environment.’ Reviewing the evidence under customary international law, the ICJ stated in paragraph 393:
The Court is of the view that a clean, healthy and sustainable environment is a precondition for the enjoyment of many human rights, such as the right to life, the right to health and the right to an adequate standard of living, including access to water, food and housing. The right to a clean, healthy and sustainable environment results from the interdependence between human rights and the protection of the environment. Consequently, in so far as States parties to human rights treaties are required to guarantee the effective enjoyment of such rights, it is difficult to see how these obligations can be fulfilled without at the same time ensuring the protection of the right to a clean, healthy and sustainable environment as a human right. The human right to a clean, healthy and sustainable environment is therefore inherent in the enjoyment of other human rights. The Court thus concludes that, under international law, the human right to a clean, healthy and sustainable environment is essential for the enjoyment of other human rights.
Judge Dire Tladi, in his Declaration, denied that there was any real ambiguity in the above-quoted statement. Although some might think the ICJ had failed to choose between the right to a healthy environment as a self-standing right and the idea that environmental harm affects various more conventional human rights, he argued: ‘that a right can exist as a self-standing right and, at the same, be essential for the achievement of other rights is not only possible but quite normal’. What resolved any doubt, in his view, was that ‘the Court explicitly refers to a right to a clean and healthy environment as a precondition for the enjoyment of other rights,’ which differs from a merely empirical claim (paragraph 28 of the declaration, with emphasis in the original).
In my chapter on ‘The Status of the Right to a Clean, Healthy, and Sustainable Environment under Customary International Law’ in a booklet on ‘Intellectual Property and the Human Right to a Healthy Environment’ edited by Elena Izyumenko, I looked at this issue in more detail.
3. Future Generations
The IACtHR understood the right to a healthy environment as a commitment to both present and future generations. In doing so, the IACtHR distinguished between a collective and individual dimension of the human right to a healthy environment (paragraph 272 of its opinion):
The human right to a healthy environment has been understood as a fundamental right for the existence of humanity, with both individual and collective connotations. In its collective dimension, this right constitutes a universal value that is owed to both present and future generations. That said, the right to a healthy environment also has an individual dimension insofar as its violation may have direct or indirect repercussions on the individual owing to its connectivity with other rights, such as the rights to health, personal integrity and life, among others.
It explicitly invoked intergenerational equity (paras. 305-313), linking it to the human right to a healthy climate, which the IACtHR considered an essential element of the human right to a healthy environment (paragraph 311):
The Court underscores that the purpose of the obligations arising from the right to a healthy climate is to protect the global climate system for the benefit of humanity as a whole, and both present and future generations are part of this. The Court notes that, even though international human rights law recognizes that everyone is a possessor of non-derogable rights, the ethical and legislative grounds for this transcend those who inhabit the planet today, extending also to humanity as a legal and moral community that endures over time.
Notably, the IACtHR added to this that ‘climate change has greater effects on those who, today, are very young and who must live their whole lives in a climate environment that is increasingly adverse. Similarly, owing to their age, older persons are more vulnerable in a context of climate risks that increase day by day’ (paragraph 312). The IACtHR thus showed an awareness that there is a distinction to be made within the current generation between the young, the old, and the others. The IACtHR came to the following conclusion (paragraph 313):
Consequently, the guarantee of intra- and intergenerational equity is essential for the interpretation and implementation of the obligations arising from the right to a healthy climate because this right, in its collective dimension, seeks the comprehensive protection of humanity as a whole.
The ICJ also referred to the principle of intergenerational equity, understood as ‘expression of the idea that present generations are trustees of humanity tasked with preserving dignified living conditions and transmitting them to future generations’ (paragraph 156), in a general sense. In the ICJ’s view, this principle served only as general interpretive guide and not specifically as element of the right to a healthy environment or any more specific obligation under international law (paragraph 157):
In the Court’s view, intergenerational equity is a manifestation of equity in the general sense and thus shares its legal significance as a guide for the interpretation of applicable rules. Accordingly, considerations of intergenerational equity must play a role infra legem, without displacing or exceeding the limits of the applicable law. Due regard for the interests of future generations and the long-term implications of conduct are equitable considerations that need to be taken into account where States contemplate, decide on and implement policies and measures in fulfilment of their obligations under the relevant treaties and customary international law.
Neither the ICJ nor the IACtHR explicitly recognised individual members of future generations as present holders of a justiciable right to a healthy environment. The IACtHR, however, characterised the right to a healthy environment as protecting both present and future generations and framed environmental protection in strongly intergenerational terms. By contrast, the ICJ discussed intergenerational equity as a general principle or consideration in environmental law, but did not expressly connect it to a right to a healthy environment.
4. Nature as Rights-Holder
The IACtHR stressed the increasingly strong interdependence of humans and our environment, and believed this should be reflected in our interpretation of international law. In paragraph 282, the IACtHR recalled that, pursuant to Article 29 of the American Convention,
[…] the interpretation of the rights protected by the Inter-American system must be guided by an evolutive perspective in keeping with the progressive development of international human rights law. Thus, recognition of Nature as a subject of rights does not introduce content that is alien to the Inter-American corpus iuris but rather represents a contemporary expression of the principle of the interdependence between human rights and the environment. This interpretation is also aligned with advances in international environmental law which has established structural principles such as inter-generational equity, the precautionary principle, and the duty of prevention, all aimed at preserving the integrity of the ecosystems in the face of current and future threats
In subsequent paragraphs, it seems that the IACtHR moved beyond this idea of interdependence, and regarded Nature as autonomous subject of protection. The IACtHR ‘note[d] a growing tendency in legislation and case law to recognize Nature as a subject of rights’ (paragraph 286). In support, the IACtHR referred to developments in domestic law across the Americas, in India, and it mentioned a ruling of the Erfurt District Court (Germany). And then, in paragraph 315, the IACtHR noted that ‘the right to a healthy climate relates not only to present and future generations, but also to Nature, conceived as the physical and biological foundation of life’. Nature is ‘entitled to autonomous legal protection’ (paragraph 316), which suggests that the right to a healthy environment protects it even without proof of harm to a specific individual or group of individuals.
In its climate advisory opinion, the ICJ did not take this step. Instead, as already explained above, it treated environmental protection primarily as a prerequisite for the enjoyment of human rights.
5. Peremptory Norms (Jus Cogens) and Erga Omnes Obligations
The IACtHR considered the prohibition against causing massive and irreversible environmental damage to be a peremptory norm (jus cogens) (paragraphs 287-294). Note that it did not believe the right to a healthy environment itself had this peremptory status. This suggests that the IACtHR reserved peremptory status for particularly egregious forms of environmental harm. Causing massive and irreversible environmental damage implies, at the very least, a profound disregard for environmental protection, making such conduct qualitatively more serious than an ‘ordinary’ breach of the right to a healthy environment.
The ICJ took a different route. It said nothing about jus cogens but did affirm that many climate-related duties - such as preventing significant environmental harm and cooperating internationally - are obligations erga omnes, i.e., obligations that are owed to the international community as a whole (paragraphs 439-443). The two courts thus moved in different directions: the ICJ stressed erga omnes obligations, while the IACtHR stressed jus cogens and barely mentioned erga omnes. In any case, the labels were not attached explicitly to the human right to a healthy environment.
6. Corporate Responsibility
Finally, both opinions said little about corporate obligations. The ICJ remained largely silent on direct corporate responsibility.
The IACtHR framed responsibility primarily through State duties to regulate companies within their jurisdiction or control (see paragraphs 345-351). In view of the IACtHR (para. 345):
States should adopt legislative and other measures to prevent human rights violations committed by public and private enterprises and, when these occur, investigate them, punish them, and guarantee redress for their consequences. Ultimately, this is an obligation that should be complied by the business sector and must be regulated by States, which are the subjects of international law over which the Court exercises jurisdiction.
This is noteworthy because other courts, including the Hague Court of Appeal in the Shell case, have recognized that corporations have duties derived more directly from the internationally recognized right to a healthy environment. In this respect, the IACtHR was perhaps not as progressive and adventurous as it was with respect to the other legal dimensions of the right to a healthy environment discussed above.
Concluding Observations
The comparison shows that both advisory opinions firmly establish the right to a healthy environment within contemporary international law, while doing so through different legal techniques and with different results. The IACtHR adopts a more expansive and innovative approach, recognising the right as autonomous, extending its reach to future generations and, to some extent, Nature itself. The ICJ, by contrast, takes a more cautious approach, grounding the right in existing human rights law and customary international law while emphasising its indispensable role in the enjoyment of other human rights. Together, these opinions significantly advance the international recognition of the right to a healthy environment, even if important questions about its legal consequences remain open.
Bio
Otto Spijkers is assistant professor of international and European law at Leiden University College (LUC), Faculty of Governance and Global Affairs of Leiden University. Before joining Leiden University College, Otto was professor of international law at Wuhan University’s China Institute of Boundary and Ocean Studies as well as its Research Institute of Environmental Law. Prior to joining Wuhan University, he worked at the Utrecht Centre for Water, Oceans and Sustainability Law and Netherlands Institute for the Law of the Sea of Utrecht University, Netherlands. He wrote his doctoral dissertation, entitled The United Nations, the Evolution of Global Values and International Law, at the Grotius Centre for International Legal Studies of Leiden University.