Climate Justice at the ICJ: Human Rights Implications of the Advisory Opinion
By Margaretha Wewerinke-Singh, Annalisa Savaresi, Claudia Ituarte-Lima and Corina Heri
This blog post was first published on GNHRE (30 August 2025).
The International Court of Justice’s landmark Advisory Opinion on the Obligations of States with Respect to Climate Change delivered on 23 July 2025 has unequivocally placed human rights at the centre of the applicable law on climate change. With it, the International Court of Justice (ICJ) has consolidated the growing consensus on a global body of law on climate change grounded in human rights norms and obligations. The Advisory Opinion was adopted unanimously by all ICJ judges, signalling consensus on the interpretation of international obligations concerning climate change. Although not legally binding, the Court’s authoritative interpretation carries considerable weight. While cautious in parts, the Opinion nonetheless sets a clear normative direction that is likely to shape climate litigation, legislation, and diplomacy in the years ahead. Unsurprisingly, the Advisory Opinion has prompted extensive international commentary, particularly regarding its interpretation of States’ human rights obligations (see e.g. Boyd, Heri, McVey and Savaresi, Perera and Wewerinke-Singh and Viñuales). This post examines the human rights relied upon and developed in the ICJ’s Advisory Opinion and explores how its interpretation interacts with recent pronouncements of the European Court of Human Rights (ECtHR), the Inter-American Court of Human Rights (IACtHR), and relevant domestic and transnational practice.
Human rights within and beyond the Advisory Opinion
Spearheaded by the Pacific Islands Students Fighting Climate Change, the Advisory Opinion campaign before the ICJ catalysed unprecedented public participation, engaging youth and children, civil society organisations, as well as nature conservation and human rights groups (see e.g. Samuels, Peel and Neil, and Ituarte-Lima).
The ICJ’s detailed analysis of States’ human rights obligations proceeds along three tracks. First, the Court recognises that the effective enjoyment of human rights depends on a healthy environment and canvasses how climate change impairs specific rights (paras 372-386). Second, it turns to the implications of the right to a clean, healthy and sustainable environment (paras 387-393). Finally, the Court characterises States’ climate-protection obligations as erga omnes, and details the legal consequences associated with these. Several of the judges’ separate opinions further elaborate on these points, enriching the development of human rights law in relation to climate change.
The Advisory Opinion unequivocally asserts that environmental protection is a precondition for the enjoyment of a range of human rights— specifically mentioning those to life, health, an adequate standard of living, privacy, family and home, as well as the rights of women, children and Indigenous peoples. This position aligns the ICJ with the growing body of international, regional, and national practice recognising the interdependence between the enjoyment of human rights and the protection of the climate system. Since 2009, UN human rights bodies and special mandate holders have articulated the implications of human rights obligations for climate action, including through a series of Human Rights Council resolutions. In 2021, these activities culminated with the appointment of a UN Special Rapporteur on the promotion and protection of human rights in the context of climate change. In recent years, the rapidly expanding body of domestic jurisprudence recognising the links between human rights and climate law obligations—following the landmark Leghari v Pakistan judgement—was corroborated at the regional level by the 2024 judgment by the ECtHR in KlimaSeniorinnen et al v Switzerland and the 2025 Advisory Opinion of the IACtHR on the Climate Emergency and Human Rights. The ICJ’s Advisory Opinion explicitly references some of these milestones, and several separate opinions by the judges further elaborate on them.
The ICJ’s Advisory Opinion also specifically considers the role of the right to a clean, healthy and sustainable environment vis-à-vis climate change. As Boyd and Heri have also noted, this is not a mere rhetorical exercise. Rather, the Advisory Opinion crystallizes the position of this right within the applicable law, making it an integral part of State obligations regarding climate change. The Court stops short of explicitly recognising the right to a clean, healthy, and sustainable environment as a rule of customary international law, or of defining its normative content. This caution likely reflects three factors: the lack of recognition by powerful States, differing interpretations across legal systems, and a deliberate choice to leave space for human rights bodies to further develop the right in practice. Nonetheless, some judges, in separate opinions, went further, drawing on domestic constitutions, regional jurisprudence, and United Nations practice and concluding that the right either already constitutes customary international law or is rapidly crystallizing as such. Judge Bhandari, Judge Aurescu and Judge Tladi emphasise its customary status, with Judge Aurescu—who raised a question on this at the ICJ hearings—explicitly grounding the right in widespread domestic recognition, regional jurisprudence, and UN resolutions. Judge Charlesworth explores the content of the right, emphasizing that its procedural and substantive features and special obligations towards those in vulnerable situations. Judge Sebutinde further underscores that the law must consider the interests of “present and future generations.”
Although the ICJ did not explicitly delineate the substantive elements of the right to a healthy environment, its references to climate, food, and water—anchored in IPCC evidence—clarify how these dimensions are interconnected and mutually reinforcing (para. 384). The Advisory Opinion highlights the composite character of the right and its dependence on ecological integrity. While the Court did not directly address the environmental democracy dimensions of the right—namely access to information, public participation, and access to justice—its recognition of the International Covenant on Civil and Political Rights as a key instrument for climate-related obligations implicitly underscores the centrality of procedural rights, such as freedom of assembly and expression, for protecting individuals and groups from climate harms.
The Advisory Opinion integrates national and regional jurisprudence, the work by international bodies, and IPCC scientific assessments to clarify the heightened obligations of States toward vulnerable populations. The Court uses IPCC findings to articulate the causal links between climate change and the impairment of human rights under the International Covenant on Civil and Political Rights and the International Covenant on Economic, Social and Cultural Rights. It particularly highlights how historically marginalized groups—especially women and Indigenous peoples—are disproportionately affected (paras. 77, 384). Judge Charlesworth provides a more developed intersectional analysis of climate impacts, concluding 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” (para. 29).
Finally, the Advisory Opinion characterises States’ climate-protection obligations—including the prevention duty under the no harm rule—as erga omnes, thus linking the human rights implications of climate harm to obligations owed to the international community as a whole. This finding— grounded on human rights as part of the legal framework applicable to climate change and erga omnes obligations as their corollary— powerfully confirms the crucial role of human rights in climate governance and is especially consequential. It connects shared human rights interests in a stable climate to obligations enforceable by all States, and not only by those specially injured. This interpretation potentially unlocks forms of invocation of responsibility that do not depend on bilateral injury and that reflect the distributive and intergenerational nature of climate harm (see further Pezzano). It also aligns the Court’s reasoning with domestic court decisions—such as Urgenda v the State of the Netherlands —which held that difficulties of attribution and causation do not exempt wrongful conduct from legal consequences.
Future generations: from equity infra legem to rightsholders
The Advisory Opinion weaves intergenerational equity into the legal principles applicable to climate change (paras. 155-157). It treats intergenerational equity as a legal consideration that guides the interpretation and application of obligations—both treaty-based and customary—rather than as a self-standing source of obligation. In our reading, this is a choice of legal technique rather than a denial of normative salience. By placing future generations within the infra legem toolbox, the Court ensures that obligations are construed and applied in ways that avoid shifting intolerable burdens to those yet to be born. As Nolan also notes, however, regional human rights courts have moved further toward recognising future generations as rightsholders and toward using general principles to operationalise those rights.
In its 2025 Advisory Opinion, the IACtHR stresses “life in dignity,” warns against “ecological barbarism,” and reads intergenerational considerations not only as interpretive constraints but as organising reasons for action. This is a distinct jurisprudential move, one that foregrounds principles to concretise obligations owed to those not yet born. In doing so, the IACtHR draws on general principles—precaution, prevention, intergenerational equity—and softlaw instruments —such as the Maastricht Principles on the Human Rights of Future Generations — to frame States’ duties toward “present and future generations of humanity” in climate governance. The Maastricht Principles articulate present generations’ duties to avoid foreseeable harm to future generations, to cooperate internationally, and to act as stewards of natural systems. Their influence is evident in the IACtHR’s Advisory Opinion and in domestic practice, and it also resonates with the ICJ’s unanimous decision to treat intergenerational equity as an interpretive lens shaping the content of due diligence over time.
By contrast, in KlimaSeniorinnen et al v Switzerland, the ECtHR based its reasoning on Article 8 of the European Convention on Human Rights, interpreted in conjunction with State obligations under the UNFCCC and the Paris Agreement. The Court conceptually recognised the “intergenerational burdensharing” dimension of mitigation, but the doctrinal foundation rested on Article 8’s positive obligations, informed by climate science and international climate law indicators of adequacy. On standing, the ECtHR broke with its established doctrine by accepting the association’s representative claim precisely because climate change presents diffuse, systemic and intergenerational risks.
Despite their differing approaches, all three courts clearly emphasised the intergenerational dimension, paving the way for the crucial conceptual shift needed to recognize future generations as right-holders.
This shift is already manifest in the swelling body of domestic practice, translating intergenerational equity reasoning into enforceable rights. The Philippine Supreme Court’s landmark 1993 Oposa ruling treated intergenerational responsibility as a justiciable basis for standing and for constraints on resource depletion. In 2018, the High Court of Bogotá acknowledged the rights of future generations and of the Amazon, ordering the government to adopt a plan to halt deforestation. In 2021,the Neubauer judgment by the German Federal Constitutional Court found that excessive delays in emission reductions violate constitutional rights by disproportionately placing mitigation burdens onto younger and future generations. Together, these lines of authority mark a shift from equity infra legem to concrete obligations and remedies, which shaped the ICJ’s interpretation of the normative landscape and are poised to guide other courts in future.
The trend is visible across jurisdictions. The Grantham Research Institute’s 2025 snapshot identifies a further uptick in cases engaging human rights arguments, youth claimants and intergenerational reasoning, with courts increasingly scrutinising the adequacy of national pathways against science-based indicators and international commitments. This picture reinforces the role of human rights as a vehicle for translating climate objectives into State duties, including duties owed to those not yet born.
Systemic integration, duty of cooperation and good faith
The ICJ’s Opinion is a sustained exercise in systemic integration. Throughout its opinion, the Court reads treaty obligations in light of one another and of general international law, including human rights—doing precisely what Article 31(3)(c) of the Vienna Convention on the Law of Treaties prescribes: interpreting treaties “in the light of any relevant rules of international law applicable in the relations between the parties”. Thus, the climate treaties’ provisions are construed in a manner that factors in the human rights implications of climate harm and the collective temperature goals implications for State obligations concerning climate change mitigation and finance. The ICJ aligns with the ECtHR’s —and, before it, the Dutch courts’—“integrated reading” of the European Convention on Human Rights alongside the UN Framework Convention on Climate Change and the Paris Agreement, confirming that this approach should be regarded as the general interpretive ethic for this complex legal field. Rejecting the view that climate change treaties alone constitute the relevant law, the ICJ interprets them in conjunction with other environmental agreements of particular human rights significance—namely the Convention on Biological Diversity and the Desertification Convention—framing these instruments as part of the directly applicable legal framework (paras. 113–171, 172).
The Advisory Opinion also affirms that the duty to cooperate has customary force and is governed by good faith. In doing so, the ICJ connected good faith cooperation to human rights in two ways. First, by recognising that the protection of the climate system is an erga omnes concern, it aligns the cooperative duties that make mitigation possible with interests shared by all peoples, including future generations. Second, by affirming that environmental protection is a precondition for human rights enjoyment and by engaging the right to a clean, healthy and sustainable environment, it treats human rights norms as part of the matrix that informs what due diligence and cooperation require in concreto.
The Opinion’s Contribution and Future Directions
The ICJ’s views on States’ human rights obligations provide a clear normative direction for future climate law-making and enforcement, likely to shape future climate litigation, legislation, and diplomacy.
On mitigation, the ICJ clarifies that equity and the principle of Common but Differentiated Responsibilities and Respective Capabilities shape States’ obligations broadly, while endorsing the ECtHR’s approach by translating intergenerational concerns into concrete governance requirements on targets, pathways, and credible implementation—likely influencing proportionality and adequacy reviews in other jurisdictions.
On cooperation, the ICJ aligned with the International Tribunal on the Law of the Sea’s Advisory Opinion on Climate Change by emphasizing good faith and due diligence, and supporting closer scrutiny of whether finance, technology, and capacity-building measures are commensurate with the Paris Agreement’s temperature goals and evolving capabilities.
On extraterritorial effects, the ICJ indicates that human rights obligations related to climate change must be interpreted instrument by instrument, yet cannot be limited to a narrow territorial perspective when the harm is inherently transboundary.
On participation and remedies, the United Nations Committee on the Rights of the Child’s General Comment No. 26 and the UN General Assembly’s recognition of the right to a clean, healthy, and sustainable environment have become key interpretive anchors for youth and community claimants seeking forward-looking relief.
As noted above, the Court left open the question of whether the right to a clean, healthy, and sustainable environment has attained customary status. However, the Court’s systematic engagement—together with its treatment of erga omnes obligations—signals a readiness to treat human rights norms as interpretive constraints on both treaty and customary law in the climate context.
In sum, the Opinion makes crystal-clear that human rights norms—both treaty-based and customary—are essential reference points for defining States’ climate obligations, including those owed to future generations. This marks a significant advance, establishing a human rights–based approach to climate change that recognises time as a distinct and relevant dimension.
With its Advisory Opinion, the ICJ has not drafted a human rights code for the climate emergency. Rather, it has taken a subtler—and potentially more influential—approach: mainstreaming human rights and the interests of future generations into the interpretation of climate treaties and customary law, reinforcing the duties of cooperation and due diligence through human rights standards, and reframing climate protection duties as erga omnes obligations. Read alongside the other landmark climate rulings cited above, the ICJ’s Advisory Opinion consolidates a transnational body of emerging global law on climate change grounded in human rights norms and obligations. The task for lawmakers, implementers, and practitioners is to use this evolving corpus of law to craft rules that prevent further harm to present and future generations—and to redress harms already suffered.