The ICJ’s advisory opinion has, in essence, called a new tune for the global climate dance, a stark departure from the hesitant diplomatic shuffle we’ve witnessed for years. No longer can states comfortably sit on the sidelines, content with the old, slow waltz of diplomatic niceties and legal ambiguities that once limited international climate justice. The Court has clarified the choreography, affirming that there are not just moral but binding legal obligations to act, grounded in human rights, environmental law, and customary international law.
For years, climate change litigation between nations felt like a diplomatic dance in which everyone knew the steps but no one dared to lead. States, despite the planet’s ever-warming temperature, largely shied away from suing each other, citing everything from ‘it’s complicated’ legalities to the sheer awkwardness of confronting powerful allies. As we discussed in our earlier piece, these were the legal and diplomatic limitations of international climate justice. But mark your calendars, because 23rd July, 2025 just rewrote the choreography entirely.
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On that day, the International Court of Justice (ICJ), the principal judicial organ of the United Nations, issued its unanimous advisory on the obligations of States concerning climate change. This was undoubtedly a landmark moment for the court, climate action, and the law, offering legal guidance on the scope of the duties of states under international law, while potentially reshaping the strategic and normative landscape for future climate accountability.
The relentless advocacy of youths from the small Pacific Island State of Vanuatu triggered this pivotal decision. They successfully lobbied a coalition of 132 nations, culminating in the United Nations General Assembly (UNGA) Resolution 77/276, which formally requested an ICJ advisory clarifying the international legal obligations of states to protect present and future generations from climate change’s adverse effects. On 29 March, 2023, the UNGA adopted this resolution by consensus, underscoring the member states’ keen interest in the Court’s consideration.
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The questions before the court were as follows:
- What are the obligations of States under international law to ensure the protection of the climate system and other parts of the environment from anthropogenic emissions of greenhouse gases, with regards to States, alongside present and future generations?
- What are the legal consequences under these obligations for States, where they, by their acts and omissions, have caused significant harm to the climate system and other parts of the environment, concerning:
- States, including in particular small island developing States, which due to their geographical circumstances and level of development are injured or specially affected by or are particularly vulnerable to the adverse effects of climate change?
- People and individuals of the present and future generations affected by the adverse effects of climate change?”
In response to the first question on the obligations of States, the ICJ, in its groundbreaking opinion, unanimously stated that climate change treaties (UNFCC, Kyoto Protocol, Paris Agreement, UNCLOS) set forth binding obligations for State parties, as beyond these treaties, under customary international law, international human rights law, the law of the sea and other instruments, that they have clear obligations to ensure the protection of the climate system and other parts of the environment from anthropogenic greenhouse gas emissions.
Under customary international law, states must prevent significant environmental harm (paras. 272-300) and cooperate in addressing climate change (paras 301-308). International human rights law further imposes obligations to protect rights affected by climate change, such as life, health, housing, food, and water, including the fundamental right to a clean, healthy, and sustainable environment (paras 369-404).
…the court opined that rules of State responsibility apply to breaches of climate obligations (paras 405-420), and States can be held internationally responsible for failing to regulate key drivers of emissions, including fossil fuel production, energy consumption, issuance of exploration licenses, and subsidies for fossils fuels (para 427). Equally, these obligations are erga omnes – owed to the international community as a whole (paras 439-443).
The precautionary principle, equity and intergenerational equity, guide the interpretation of legal obligations (paras 146-161). The precautionary approach informs the due diligence obligations of States, requiring them to anticipate, assess and avoid environmental harm, even in the face of uncertainty (paras 293-294). Equity, in this context, requires a fair distribution of burdens and responsibilities among states. This includes recognising historical responsibility, different levels of development and capacity to act, and considering the rights and needs of vulnerable populations.
Crucially, the Court clarified that broader international law applies, meaning countries not party to the Paris Agreement or those wishing to withdraw, like the US, are still obligated to protect the environment, including the climate system. With this, the Court definitively laid to rest the argument that climate treaties are lex specialis – laws governing only a specific subject matter (paras 162-171).
Furthermore, the Court stated that states have obligations of conduct (to take steps) and obligations of result (to achieve goals such as Nationally Determined Contributions, NDCs) (paras 174-270). This also includes the obligation to cooperate through finance, technology transfer, and capacity building under both treaty and customary law (paras 214-218, 260-267, 301-308).
The duty of due diligence applies across all these obligations, and the standard is stringent, particularly regarding the implementation of mitigation and adaptation efforts (paras 281-294, 250-254, 255-259).
In response to the second part of the question on consequences under these obligations for States, the court opined that rules of State responsibility apply to breaches of climate obligations (paras 405-420), and States can be held internationally responsible for failing to regulate key drivers of emissions, including fossil fuel production, energy consumption, issuance of exploration licenses, and subsidies for fossils fuels (para 427). Equally, these obligations are erga omnes – owed to the international community as a whole (paras 439-443).
Major emitters now face direct accountability, as customary international law applies to all States, including those not party to climate treaties. A State’s obligations are not determined solely by its treaty status or by general categorisations like ‘developing country’; instead, they are assessed in light of their current capabilities and responsibilities for global emissions (para 297). This brings high-emitting countries like the US, China, and India under scrutiny, even if they are not parties to certain treaties (e.g., the US to the Kyoto Protocol) or are classified as developing states under various treaty regimes.
What happens next depends entirely on whether governments, civil society, and the international community choose to truly embrace this new rhythm, aligning national priorities with these newfound legal obligations. The time for hesitant steps is over; it’s now up to us to ensure this isn’t just a change in the music, but a full-fledged, urgent, and collective performance for climate justice, ensuring a livable future for generations to come.
Legal consequences of breaches include cessation of wrongful act, guarantees of non-repetition, reparation including restitution, compensation, satisfaction (paras 444-445). Each injured State may invoke the responsibility of every State that has caused harm through internationally wrongful acts, even if many States contributed cumulatively (para 438). Finally, the obligations to protect people, especially the vulnerable and future generations, are reinforced by human rights frameworks.
A pertinent question following the delivery of this landmark opinion is its implications to the climate justice terrain. While the ICJ’s advisory opinions are formally not binding, they regularly set legal and political frameworks prompting measurable action, often through UN resolutions, international negotiations or shifts in domestic or third-state behaviour. It is projected to be used as early as next week in national courts outside of the ICJ.
Previous ICJ advisory opinions have been implemented by governments, including when the UK agreed to hand back Chagos Islands to Mauritius in 2024. Another example is its advisory on the Namibian Mandate in 1971.
The Court’s opinion has reasonably provided a clear legal benchmark with respect to climate change related obligations, removing earlier perceived ambiguities surrounding them. With legal clarity, the climate regime is strengthened. The 2024 Baku Climate Change Conference concluded years of negotiations on modalities for setting up the Paris Agreement. However, parties failed to agree on implementing the outcomes of the Global Stocktake (GST), which was disappointing, given the critical importance of NDC 3.0 in avoiding an overshoot of the 1.5°C goal. The Court’s advisory opinion has currently affirmed that limiting global warming to 1.5ᵒC is not merely aspirational but a legally binding target under the Paris Agreement and international law (para 224).
The ICJ’s advisory opinion has, in essence, called a new tune for the global climate dance, a stark departure from the hesitant diplomatic shuffle we’ve witnessed for years. No longer can states comfortably sit on the sidelines, content with the old, slow waltz of diplomatic niceties and legal ambiguities that once limited international climate justice. The Court has clarified the choreography, affirming that there are not just moral but binding legal obligations to act, grounded in human rights, environmental law, and customary international law. While the opinion itself isn’t a direct order, its authority carries immense weight, empowering vulnerable states and putting high-emitting nations and fossil fuel actors firmly on the dance floor. If history is any guide, this legal clarity will catalyse new global norms and influence real-world change.
What happens next depends entirely on whether governments, civil society, and the international community choose to truly embrace this new rhythm, aligning national priorities with these newfound legal obligations. The time for hesitant steps is over; it’s now up to us to ensure this isn’t just a change in the music, but a full-fledged, urgent, and collective performance for climate justice, ensuring a livable future for generations to come.
Ruth Soronnadi is a lawyer and West Africa regional coordinator for the Climate Parliament, while Tobi Oluwatola is a policy analyst and CEO of TAO Technologies, a climate technology company.
