The ICJ Advisory Opinion on Climate Change: A Business and Human Rights Perspective

[Marisa McVey is a lecturer in law at Queen’s University Belfast.

Annalisa Savaresi is professor of international environmental law at the Centre for Climate Change, Energy and Environmental Law, University of Eastern Finland. She also holds a part-time Chair in environmental law at the University of Stirling, Scotland.]

State obligations in relation to climate change have come under increasing scrutiny by international courts in recent years. In July 2025, it was the turn of the International Court of Justice (ICJ) to hand down its long-awaited Advisory Opinion on state obligations concerning climate change under international law. While the Opinion focuses on the conduct of states, it has potentially far-reaching consequences for the regulation of private emitters. In this post, we examine the implications of the Opinion for human rights-based corporate responsibility. This focus is particularly significant given the substantial contribution of corporate actors to global emissions, and the growing trend of framing their climate-related harms in terms of breaches of human rights obligations in litigation. 

The ICJ Advisory Opinion in a Nutshell

After years of speculation and intense campaigning, in 2023 the UN General Assembly formally submitted a request for an Advisory Opinion on state obligations concerning climate change (UNGA resolution 77/276). The request formulated two carefully worded questions, concerning the content and scope of states’ international legal obligations to protect the climate system and the environment; and the legal consequences associated with said obligations, vis-à-vis significant harm to the climate system and the environment (UNGA resolution 77/276, para. 1)

In delivering its unanimous Opinion, the Court described climate change as an ‘urgent and existential’ threat (ICJ Advisory Opinion para. 73). As it elucidated states’ international law obligations, the ICJ maintained that they have a duty to prevent significant harm to the climate system by exercising due diligence and using all means at their disposal to prevent activities carried out within their jurisdiction or control from causing said harm (para. 457). The Court further asserted that breaches of ‘any of the obligations’ identified in the Opinion could potentially constitute an internationally wrongful act (para. 207), thereby potentially engaging the international responsibility of the state concerned (para. 457). 

Even more crucially, the Court found that States’ obligations ‘pertaining to the protection of the climate system and other parts of the environment from anthropogenic GHG emissions, in particular the obligation to prevent significant transboundary harm under customary international law’ are owed erga omnes (para. 440). This means that all states—or all state parties, depending on the international law provisions invoked—have a legal interest in ensuring compliance, which entitles them to invoke the responsibility of other states that fail to meet these obligations.

In identifying the applicable law, the Court acknowledged the relevance of a broad body of international instruments extending beyond the climate treaties (namely, UNFCCC, Kyoto Protocol and Paris Agreement). It thus aligned with much of the current literature and with ITLOS’s 2024 Advisory Opinion— in finding that climate treaties are not the only relevant instruments for determining the scope of state obligations in this area. By accepting this premise, the ICJ explicitly rejected the lex specialis argument put forward by some participants in the proceedings (para. 171). 

The Court then elaborated on the scope and content of state obligations under international climate treaties, other environmental agreements, customary international law, and human rights law. Most crucially for present purposes, state obligations in this connection include the duty to regulate the conduct of private actors (para. 428). This post therefore specifically focuses on those sections of the Opinion that are most relevant from the perspective of human rights-based corporate responsibility.

Climate Change, Business and Human Rights

The Opinion unequivocally affirmed that human rights obligations—derived both from treaty and custom—form an integral part of the applicable legal framework concerning climate change (para. 145). It also explicitly recognised that the adverse effects of climate change may impair the effective enjoyment of a wide range of human rights (para. 386), including 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 recognizing the interdependence between the enjoyment of human rights and the protection of the climate system (para. 393). This practice encompasses a series of resolutions by the Human Rights Council; the 2025 Advisory Opinion of the Inter-American Court of Human Rights on the Climate Emergency and Human Rights; the 2024 judgment delivered by the European Court of Human Rights in KlimaSeniorinnen et al v Switzerland, as well as a plethora of national courts decisions handed down since the landmark case Urgenda v the State of the Netherlands. 

The ICJ asserted that states should undertake regulatory measures that are designed to achieve ‘deep, rapid, and sustained GHG emissions’ (para. 282). These measures must regulate the conduct of public and private operators within the states’ jurisdiction or control and be accompanied by effective enforcement and monitoring mechanisms to ensure their implementation (Urgenda v the State of the Netherlands). 

Rather crucially, the Court asserted that a state’s failure to take appropriate action to protect the climate system — including through fossil fuel production, fossil fuel consumption, the granting of fossil fuel exploration licences or the provision of fossil fuel subsidies — may constitute an internationally wrongful act which is attributable to that state (para. 427). Some participants in the proceedings had argued that the application of the rules on State responsibility is difficult in the context of climate change, since the emission of GHGs is not an internationally wrongful act and difficulties arise for its attribution (para. 426). Instead, the ICJ found that a state may be held responsible where it fails to take the necessary regulatory and legislative measures to limit the quantity of emissions caused by private actors under its jurisdiction (para. 428). In this connection, the wrongful act is not the emissions of GHGs, but failure to regulate. This interpretation of state obligations is entirely consistent with the ICJ’s jurisprudence on environmental harm (including Pulp Mills on the River Uruguay and Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v. Nicaragua) and Construction of a Road in Costa Rica along the San Juan River (Nicaragua v. Costa Rica as well as with the caselaw of regional courts (most recently, Cannavacciuolo and Others v. Italy and Case of the Inhabitants of La Oroya v Peru). The ICJ’s Opinion furthermore affirmed that, in principle, the rules on State responsibility can address a situation in which there exists a plurality of injured or responsible States (para. 430).

While concurring with their peers, Judges Bhandari and Cleveland issued a joint declaration, arguing that the Court could have taken a stronger stance, given the ‘outsized’ role of fossil fuels in driving anthropogenic emission (Judges Bhandari and Cleveland, para. 4). They specifically referred to reports by the Intergovernmental Panel on Climate Change, the International Energy Agency and to state practice – including Norwegian State v. Greenpeace Nordic, Nature and Youth Norway, to elaborate on State obligations to protect the climate system, particularly regarding fossil fuel production, licensing, and subsidies. Specifically, they outlined states obligations concerning, inter alia, environmental risk assessments and the preparation and implementation of nationally determined contributions (NDCs) under the Paris Agreement. They concluded that state international obligations to mitigate the potential harms arising within their jurisdiction or control include phasing out fossil fuel dependency, directly accounting, and redressing, the downstream consequences of production, licensing and subsidy-related activities (para. 23).

Impacts and Prospects

The ICJ’s authoritative interpretation of states’ international obligations on climate change reinforces the growing body of practice on corporate accountability for climate-related harms. The Advisory Opinion derives from existing international law a clear and substantial duty for states to ensure that corporate actors within their jurisdiction or control do not contribute to harmful climate impacts. As further clarified by Judges Bhandari and Cleveland, this obligation takes on specific contours in the context of licensing oil and gas extraction.

Admittedly, the ICJ stopped well short of the more progressive position adopted by the Inter-American Court of Human Rights (IACtHR) in its Advisory Opinion issued on 3 July 2025. The IACtHR unequivocally affirmed that ‘companies are called upon to play a fundamental role in addressing the climate emergency’ and that doing so ‘is an obligation that must be fulfilled by companies and regulated by states’ (IACtHR Advisory Opinion, para. 345). The IACtHR suggested that the so-called Carbon Majors should be subject to stricter obligations (para. 353), thus aligning itself with the landmark findings of the Carbon Majors’ Inquiry by the Philippines Human Rights Commission. The IACtHR also explicitly endorsed the UN Working Group on Business and Human Rights’ holistic reading of the UN Guiding Principles on Business and Human Rights (UNGPs), which clearly links corporate climate-related harm to international human rights law (para. 346).

Unlike the IACtHR, the ICJ’s Opinion made no explicit reference to the UNGPs. The ICJ’s position is therefore more cautious and nuanced than that of the IACtHR and some domestic courts (most notably in Milieudefensie et al v Shell PLC), which have aligned with the growing body of scholarship and policy advocating for the integration of climate impacts into the ‘corporate responsibility to respect human rights’ under the UNGPs.

Even with these limitations, the ICJ’s findings are likely to have significant impacts.

First, the growing body of mandatory human rights due diligence legislation could require companies to report on their climate-related human rights impacts and to adopt emission reduction plans aligned with the Paris Agreement’s 1.5°C temperature target. The first test of this development is the ongoing and fractious debate over the proposed revision of the EU’s 2024 Corporate Sustainability Due Diligence Directive (CSDDD). The CSDDD’s revision is currently under examination, with final adoption expected in the course of 2025. Among the proposals under consideration is the controversial suggestion to remove the obligation under Article 22 of the CSDDD for companies to adopt and implement credible climate transition plans. Under the revised wording, companies would only be required to formulate an emissions-reduction plan, without any obligation to demonstrate its effective implementation. This shift appears to substantially weaken the CSDDD’s climate-related due diligence requirements and, in light of the ICJ Advisory Opinion, risks diverging from states’ obligations under international law.

Second, the ICJ Opinion may also influence the outcome of ongoing negotiations on a treaty on business and human rights. As mandated by the 2014 Human Rights Council Resolution 26/9, these negotiations are expected to deliver ‘an international legally binding instrument to regulate, in international human rights law, the activities of transnational corporations and other business enterprises’. To date, six successive drafts of the instrument have been produced. However, the current draft contains little explicit recognition of the link between private emissions and the corresponding duty of the state duty to protect the climate system under human rights law (see the commentary in McVey and Savaresi). Beyond affirming victims’ rights to remediation and ecological restoration in cases of corporate harm, the current draft makes no explicit reference to corporate responsibilities related to climate change. This marks a departure from the 2022 draft, which included explicit language on climate change, associated harms and standards, and affirmed the right to a safe, clean, healthy, and sustainable environment. This narrowing of scope is difficult to justify in light of the Advisory Opinions issued by both the ICJ and the IACtHR—a tension that will no doubt surface during the 11^th session of the negotiations in October 2025. 

Conclusion 

The ICJ Advisory Opinion marks a milestone in the history of international law. While not legally binding, it offers a veritable treasure trove of legal reasoning that is likely to remain at the centre of academic and practitioner debates for years to come, shaping the evolution of the global legal framework on climate change. The Opinion clearly affirms that states have detailed and concrete legal obligations under international law to address the climate crisis. It provides a most authoritative articulation of the intrinsic relationship between the protection of the climate system and human rights—a position likely to generate cascading legal and normative effects, including in domestic litigation concerning corporate climate impacts. Yet, for all its significance, the ICJ’s Opinion also highlights the structural limitations of international law and of its judicial function when confronted with the scale and complexity of the climate crisis. As the Court itself acknowledges, this is an ‘existential problem of planetary proportions that imperils all forms of life and the very health of our planet’ (para. 456)—a challenge that cannot be addressed by courts alone, let alone by international courts in isolation.