by Lena Winzer (FRFG Project Manager) and Jason Adolph (FRFG Intern)
On 23 July 2025, the International Court of Justice (ICJ) issued a landmark advisory opinion on “the obligations of States in respect of climate change.” The Court concluded that existing international law, so treaties, customary norms and the law of state responsibility, gives rise to binding duties on States to prevent foreseeable climate harm, to exercise precaution and stringent due-diligence measures (including regulating private actors), to assist vulnerable States with adaptation, and to treat the Paris Agreement’s 1.5°C objective as the operative benchmark for ambition. Even though the written submission is advisory in form, the opinion carves out clear legal expectations for climate mitigation, adaptation and reparative measures in a way that will shape international and domestic litigation, diplomacy and policy development for years to come.
How the world brought the Court to this moment
This opinion did not appear by accident. Its legal and political roots provide valuable insights for those interested in law as a form of moral imagination. The request to the ICJ followed an internationally coordinated campaign that began with a group of 27 students at the University of the South Pacific and expanded into a broader Pacific and global movement (Pacific Islands Students Fighting Climate Change (PISFCC) and allied networks) seeking authoritative legal clarity, as the real-world impact of sea-level rise and extreme weather had exceeded traditional safeguards. That grassroots pressure was translated into state practice through Vanuatu and regional partners, which eventually led to the passing of a United Nations General Assembly resolution in March 2023, which requested the Advisory Opinion of the Court. This pathway is especially exceptional because it shows how present (and specifically young) actors who are disproportionately affected by the long-term effects of climate change, can press the international system to recognise legal duties today: students → regional mobilisation → UNGA referral → ICJ Opinion.
Why this matters for intergenerational justice
Intergenerational justice is concerned with obligations between generations: what we owe to those who come after us, what political institutions must secure for future persons, and how present privileges and risks should be redistributed over time. The ICJ opinion advances intergenerational justice by clarifying legal obligations, acknowledging remedies for delayed harms, and reinforcing tools to protect future interests.
But what does that mean in practice?
- Transformation of the Duty from an aspirational norm to a juridical requirement
Many accounts of intergenerational justice, whether following rights-based, prudential, or capabilities-oriented views, have insisted that present generations must refrain from actions that foreseeably foreclose valuable life-plans and basic goods for future persons. What the ICJ has done is translate this ethical intuition into a legal structure: duties of prevention, due diligence and cooperation that bind States as legal actors. Furthermore, the ICJ recognised ‘intergenerational equity’ as an interpretive principle for international law (paras. 155-157). This principle assumes that current generations hold the Earth and its resources in trust for future generations to preserve dignified living conditions and pass them on to future generations. Even though this does not pose a direct obligation for States, it might be integrated into future international discussions. It remains to be seen how this identification of a principle influences State policies and future international law. By treating 1.5°C as the operational benchmark and by framing mitigation and adaptation as complementary legal obligations, the Court narrows the gap between the normative claim and the concrete duty. The obligations require strict due diligence extending to regulation of private actors, such as fossil fuel producers, making policy decisions like licensing and permitting legally significant. States must maintain continuous efforts that match their capacity, and non-developing countries under the Paris Agreement are expected to pursue more ambitious goals, leaving little room for delayed mitigation or adaptation. - Recognition of harm and reparative duties
The ICJ held unanimously that a breach of climate obligations constitutes an internationally wrongful act, entailing state responsibility. The significance of a state’s omission or failure to regulate greenhouse gas (GHG) emissions lies in the fact that the mere act of emitting GHGs is not, in itself, classified as an internationally wrongful act. Rather, state responsibility is triggered when there is a breach of specific international legal obligations to prevent or mitigate such emissions. When a state neglects to take proportionate and appropriate action in response to its obligations, it can incur various forms of international responsibility. These may include obligations to cease the harmful conduct, provide assurances or guarantees against future violations, and undertake reparative measures, which can encompass restitution, financial compensation, or other forms of satisfaction. In essence, it is the failure to uphold legal duties, rather than the emissions alone, that gives rise to accountability under international law.
In the context of forward-looking justice, it is crucial that the law now acknowledges the potential for reparative redress regarding harms with long latency periods and diffuse causation when legal standards for causation and attribution are satisfied, such as sea-level rise, coastal displacement, and the loss of ecosystems. That legal recognition helps counter the moral complacency that treats future harms as inevitable collateral damage rather than as injustice requiring remedy, creating a legal avenue for reparative justice stretching across generations. - Democratic standing for posterity
A key challenge is that future generations lack representation in current political institutions. The practical solution has always been to build institutions and legal mechanisms that act as proxies for future interests. As such, the pathway that led to the ICJ opinion from student activists securing state sponsorship leading to a UNGA referral, actually shows a practical method for remedying the representational deficit. Present-day actors, particularly those most affected, can, and must, use existing institutions to secure legal recognition that binds current custodians of the international legal order. The ICJ’s finding that “all States” have a legal interest in compliance strengthens the scope of who may invoke responsibility and press for institutional reform on behalf of posterity.
Common Questions (and short answers)
Is the opinion binding?
We should be candid about limits. Advisory opinions are not directly binding in the way contentious ICJ judgments are, and the enforcement architecture of international law remains weak. Investors may litigate under ISDS regimes, and States may resist rapid regulatory change. But the opinions carry considerable legal and political authority and will inform domestic courts, treaty bodies and policymaking. In practice, this will narrow the interpretive space for states that aim to conceal their inaction by arguing it is discretion functioning within the realms of the law.
Does the opinion require an immediate fossil-fuel ban?
The Court was explicit that states may incur responsibility for conduct that foreseeably causes harm, and that fossil fuel production, licensing and subsidies fall within the relevant “conduct” to be assessed. Several judges went further in a joint declaration, arguing that staying within 1.5°C is incompatible with new fossil-fuel extraction projects and that downstream (Scope 3) emissions must be taken into account. The legal implication is stark: issuing new exploration licences or permitting new production will, in many circumstances, carry heightened legal risk.
Will this open floodgates for investor-state claims?
On the contrary, the opinion strengthens the states’ hand. By embedding climate obligations within the framework of general international law, the Court challenges the prevailing notion that safeguarding investors’ expectations should take precedence over the imperative to prevent climate-related harm. Its reasoning paves the way for reforming investment regimes that currently hinder robust climate action.
Did the ICJ recognise the rights of future generations?
Not directly. While the UNGA’s question explicitly mentioned “peoples and individuals of present and future generations”, the Court avoided framing these as rights-holders. Instead, it embedded their protection within the principle of intergenerational equity. This omission disappoints but still leaves room for civil society and future proceedings to push further.
What comes next?
For the Foundation for the Rights of Future Generations, the ICJ opinion is a moment for policy clarity and institutional reform. We call on states to:
- Amend licensing, subsidy and permitting law so decisions are assessed against a 1.5°C-consistent benchmark and include downstream emissions (Scope 3).
- Strengthen statutory duties of care and environmental impact assessments to incorporate long-term systemic risks and intergenerational impacts.
- Enshrine legally enforceable national adaptation plans, with clear financing commitments and transparent reporting, and scale up international adaptation finance for vulnerable States.
- Reform investor-state dispute frameworks so that lawful climate measures are carved out from compensation claims, and investor expectations cannot justify breaches of international climate obligations.
- Establish or empower public institutions (future-generations commissioners, guardians or ombudspersons) with standing to litigate and to advise on long-term policy consistent with intergenerational equity.
The ICJ advisory opinion does not solve climate change. But it does something morally and legally profound: it converts the ethical claim that we owe future people a habitable planet into concrete legal expectations for states today. For intergenerational justice advocates, that is both vindication and a duty. The Court has given us clearer tools; it is now the work of civil society, parliaments and judiciaries to translate legal clarity into political will and durable institutions that protect the rights of those not yet born.