Human Rights in the ICJ’s Climate Opinion: A Comparative Evaluation – Climate Law Blog

This summer has seen two major climate advisory opinions published – first from the Inter-American Court of Human Rights (IACtHR), and then from the International Court of Justice (ICJ). Both opinions address human rights law, embedding human rights in a broader overarching framework of international law that also includes international climate treaties and customary international law. But how do these opinions compare, and what room does the ICJ leave for continuing development of human rights standards by other relevant courts and treaty bodies? This blog post explores those questions by analyzing the human rights aspects of the ICJ’s advisory opinion, and contrasting them with the findings of the IACtHR (and to a lesser degree with those of other international and regional human rights adjudicators). The analysis reveals that the rights-based findings made in the ICJ’s inaugural climate advisory opinion are not necessarily ground-breaking in terms of their scope or ambition, but that they instead serve to legitimize and encourage the climate-related findings of regional human rights courts and United Nations (UN) treaty bodies.

The ICJ’s Findings on Climate Change and Human Rights

To begin, the following summarizes the ICJ’s analysis of human rights law, which led it to find that human rights law obligates States to take climate-related protective measures aimed at mitigation and adaptation (para. 403). This includes its discussion of the lex specialis argument, the range of rights at stake, the existence of a right to a healthy environment, and the extraterritoriality of obligations. 

Human Rights Obligations Are Not Displaced by the Climate Treaties

The first building block of the ICJ’s engagement with human rights law concerned a fundamental issue: its applicability to climate change. The States involved in the ICJ climate advisory proceedings did not dispute climate change’s impact on human rights. But, several States did argue that the international climate treaties (the UN Framework Convention on Climate Change (UNFCCC) and the Paris Agreement, in particular) constitute a lex specialis to human rights law, meaning that they displace human rights obligations, rendering them inapplicable. The ICJ rejected this argument, noting long-standing recognition of the interdependence between human rights and the environment, including in case-law from the three major regional human rights courts and UN human rights treaty bodies. 

The ICJ held that, when it comes to climate change, “the core human rights treaties, including the ICESCR [International Covenant on Economic, Social and Cultural Rights] and the ICCPR [International Covenant on Civil and Political Rights], and the human rights recognized under customary international law form part of the most directly relevant applicable law” (para. 145). Notably, in this crucial phrase the ICJ did not explicitly refer to the highly relevant UN Convention on the Rights of the Child (UNCRC). 

Ultimately, the ICJ found that international human rights law must inform States’ obligations under climate treaties and customary international law, and vice versa, facilitating a harmonized interpretation of the overlapping obligations at stake (para. 404). 

Climate Change Risks Impairing a Wide Array of Human Rights

Second, the ICJ mapped the human rights impacts of climate change. Citing its own past opinions, reports of the Intergovernmental Panel on Climate Change (IPCC), and the human rights listed in the preamble of the Paris Agreement, the ICJ held that “the protection of the environment is a precondition for the enjoyment of human rights” (para. 373). It then examined the impacts that climate change threatens to have on a (non-exhaustive) array of human rights, relying on the climate-related findings of various UN human rights bodies to discuss climate change’s implications for the right to life (para. 377), the obligation of non-refoulement (para. 378), the right to health (para. 379), the right to an adequate standard of living, including access to food, water and housing (para. 380), the right to privacy, family and home, which entails an obligation to adapt to climate-related impacts (para. 381), and the rights of women, children and indigenous peoples, migrants, persons with disabilities and other people in vulnerable situations (para. 382). Additionally, it cited the principles of substantive equality, non-discrimination, participation, access to justice, transparency, and the rule of law (para. 383), and noted that climate change is already contributing to malnutrition and child mortality (para. 384).

The Right to a Clean, Healthy and Sustainable Environment Is Inherent in Other Rights

Third, the ICJ engaged with the right to a clean, healthy, and sustainable environment. During the ICJ proceedings, a number of States had invoked the existence of such a right, which the UN General Assembly recognized in 2022. Citing the indivisibility and interdependence of human rights and the high number of international, regional, and domestic instruments recognizing this right, the ICJ found that many human rights cannot be fully realized in the absence of a clean, healthy, and sustainable environment (para. 389). As a result, the ICJ opined that the right to a healthy environment is “a precondition for the enjoyment of many human rights” and “is therefore inherent in the enjoyment of other human rights”, meaning that it is “essential for the enjoyment of other human rights” (para. 393). Notably, however, the ICJ skirted the issue of explicitly declaring this right a norm of customary international law.

Human Rights Treaties Can Apply Extraterritorially

Fourth, the ICJ considered the extraterritoriality of human rights obligations. It drew on its own past case-law, where it has repeatedly established that States’ human rights obligations can apply extraterritorially (see here, here, and here, for example). Although noting the primarily territorial nature of jurisdiction, the ICJ found that States should not be allowed to escape their human rights obligations where they exercise jurisdiction abroad, and that the human rights obligations under the ICCPR, ICESCR, and UNCRC can also apply extraterritorially. Keeping its findings abstract, the ICJ highlighted that the territorial scope of human rights treaties and customary law differs without providing further clarification of what this might mean for a potential interstate climate case.

How Ground-Breaking Are the ICJ’s Findings on Human Rights Law?

The ICJ’s climate opinion has already (and understandably) been described as “historic”. But how do its findings on human rights law measure up? The following contrasts these findings with recent case-law from regional human rights courts, and in particular the IACtHR. The analysis shows that the ICJ provided an affirmation of rights-based engagement with climate change, inviting further clarifications from human rights courts and treaty bodies without, however, making particular strides over existing jurisprudence.

What Is the Status of the Right to a Healthy Environment?

Although the ICJ discussed the right to a healthy environment, its language around the status and content of this right is frustratingly vague. Several of the ICJ’s judges picked up on this in their separate opinions, with both Judge Aurescu and Judge Tladi discussing the potential to recognize this right as a norm of customary international law. 

The ICJ’s approach, which stops short of giving content to or specifying obligations entailed by this right, stands in sharp contrast to the IACtHR’s climate advisory opinion. That opinion extensively clarified this right’s autonomous role, its protection of nature as well as individuals, and the fact that it contains within it an independent human right to a healthy climate. Recognizing the right to a healthy environment as a binding, independent, and fleshed-out right with both individual and collective dimensions had important ramifications for the IACtHR’s advisory opinion. The depth of its engagement allowed for a harmonized understanding of States’ obligations across customary and human rights law, including in terms of territorial jurisdiction and the human-versus-nature conundrum of anthropocentric rights (paras. 277-278). Similar findings are decidedly missing in the approach of the ICJ – and in that of the European Court of Human Rights (ECtHR), which likewise has not recognized a right to a healthy environment, and considers itself unable to do so without explicit State consent (KlimaSeniorinnen, para. 448).

Who Are the Rights-Holders?

The recognition of rights for future generations continues to divide scholars. While courts are increasingly recognizing the importance of intergenerational burden-sharing, the question of how to frame and operationalize actual human rights entitlements for future generations without undermining attention for current impacts and future inequalities remains contentious. The ICJ did not engage with these debates, because it did not talk about the rights of future generations as rights. Instead, it understood them as part of an overarching principle of intergenerational equity (para. 156). The ICJ declared that “intergenerational equity is a manifestation of equity in the general sense,” making it a general interpretative principle that does not give rise to new rights or obligations, but must nonetheless shape States’ policies (para. 157). 

This stands in sharp contrast to the approach of the IACtHR, which leveraged its own case-law and the 2023 Maastricht Principles to recognize that the human right to a healthy environment not only guarantees a right to climate protection, but also contains a collective dimension that is owed to both present and future generations (para. 272). This in turn contributed to the IACtHR’s recognition of nature as a subject of rights, its foregrounding of sustainable development, and its acknowledgment of the jus cogens status of the obligation to protect planetary habitability (para. 290). At the same time, both courts avoided facing head-on the questions of who might represent future generations in court, or how to balance their interests against those of today’s living generations. However, both findings show a much-needed openness to broadening the temporal dimension of climate obligations, beyond present-day burdens and impacts. 

Whose Vulnerability Matters?

The ICJ’s discussion of vulnerable groups, communities, and individuals particularly affected by climate change also lacks depth. The ICJ discusses the human rights obligations that are particularly relevant in the face of climate change in an abstract way, without detailed discussion of the nature of the impacts concerned or the measures required. The ICJ also fails to discuss intersectionality, poverty, cultural heritage, or race, and its treatment of Indigenous rights is vestigial at best. The separate opinion of Judge Charlesworth, who argued that “States have a particular obligation to protect the human rights of vulnerable groups” – which requires “close attention to the potentially discriminatory effects of measures taken to respond to climate change” – stands in sharp contrast to the opinion’s foreshortened engagement with the equity implications of climate change on the sub-national level. 

This terseness is accentuated when compared to the IACtHR, which dedicated extensive attention to climate-related vulnerabilities in its own climate opinion. The IACtHR not only delved deeply into the inequalities of climate change, including global, regional, and sub-national inequalities, but it also engaged substantively with the need for a gender-based perspective, access to justice, safeguards for persons living in poverty and/or displaced by climate change, protection of environmental human rights defenders, recognition of Indigenous and traditional knowledge, and the need for a fair transition that does not jettison participation, property, land, labour, or non-discrimination rights. Overall, the difference in these approaches reveals something crucial about the underlying opinions: while the ICJ understands inequality (among States, and to a lesser degree among generations and individuals) as an interpretative consideration, the IACtHR’s understanding is transformative, substantive, and “a key factor in understanding the climate crisis” (para. 63).

What Kinds of Obligations Do States Have?

Both the ICJ and the IACtHR – like ITLOS and the ECtHR – have recognized that States are under an obligation of due diligence as concerns climate change. While the ICJ’s standard of due diligence is “stringent” (para. 246), the IACtHR’s is “enhanced” (para. 233). In this regard, the two courts diverge not so much in the nature of the standard applied, but in the level of specification that it is given. Both courts apply the precautionary principle and require mitigation and adaptation, cooperation, control over corporate actors, and environmental impact assessments, but the IACtHR also disaggregates positive, negative, and procedural obligations and foregrounds information, democratic participation, and procedural rights. 

Here, too, the brevity of the ICJ’s engagement with human rights obligations reveals something about the nature of the proceedings concerned. The ICJ was not primarily focused on individuals or even on collectives at the subnational level. Instead, it leaves the clarification of their rights to specialized treaty bodies, inviting these bodies to exercise their mandate without usurping their role. The ICJ’s abridged engagement with human rights becomes understandable if interpreted in light of the fact that it is not a human rights treaty body, but a court of general jurisdiction in a system comprising several specialized human rights bodies. Its core contribution, then, lies in legitimizing rights-based engagement by these specialized bodies, and opening the door for their further engagement.

Can Human Rights Obligations Apply Extraterritorially?

Like its consideration of the content of State’s human rights obligations, the ICJ’s treatment of these obligations’ territorial scope is also abstract. This, again, seems to leave the details of interpreting the relevant instruments – and their jurisdictional clauses – to the bodies tasked with this work: the UN human rights bodies. Here, the Court’s response may also be interpreted in another way: as an attempt to leave room for diverging approaches to extraterritorial climate obligations by human rights courts. In this regard, it can be noted that while the ECtHR has rejected the idea of an impact-based approach to extraterritorial jurisdiction, the IACtHR has accepted it (paras. 229 and 277 of its 2025 opinion, as well as its 2017 opinion on the environment). 

What Right to Reparation?

As concerns reparations obligations for breaches of human rights law, the ICJ acknowledged at least the possibility of such obligations (paras. 433, 449). Still, as Judge Sebutinde noted in her separate opinion, the Court did not clarify the standing of individuals or collectives to bring claims concerning the legal responsibility of States, arguing instead that this depends on the underlying (human rights) treaties. 

By contrast, the IACtHR’s reparations findings – while succinct for a court known for creative, hands-on approaches to remedies – require the creation of effective administrative and judicial mechanisms tailored to climate-related harms, measures to protect and restore nature, medical care for climate-related illness, compensation, and guarantees of non-repetition, including preventative measures and monitoring (para. 558). Together with its findings on cooperation, including financial and economic aid to least-developed countries, the IACtHR opinion sets the tone for the array of reparations claims that will likely be contemplated by forthcoming waves of rights-based climate litigation. However, notably, the IACtHR also stopped short of what climate litigants in some domestic proceedings have sought: a judicial indication of clear reduction targets (para. 332). 

Conclusion

There are many reasons to celebrate the ICJ’s climate advisory opinion. However, with climate litigation’s “turn to rights” now in full swing, its value lies not per se in its innovations. Instead, the ICJ’s engagement with human rights obligations signals a focus on inter-state dynamics and an effort to leave room for dedicated human rights treaty bodies. Its major contribution lies in legitimizing the rights-based approach to climate change taken by these bodies, creating space that they can flesh out of their own accord. In an age of backlash against climate rulings, consolidating the recognition that human rights and the environment are deeply intertwined, and that human rights obligations must shape States’ responses to climate change, is an achievement worth celebrating in itself. 

* The author was involved in the ICJ proceedings on behalf of the International Union for Conservation of Nature.