On 23 July 2025, the International Court of Justice (ICJ) delivered its long-awaited advisory opinion on the obligations of states in relation to climate change. The opinion was issued in response to a historic request by the United Nations General Assembly, following a campaign led by Vanuatu and other climate-vulnerable nations. The request posed two central questions: first, what are the specific legal duties of states under international law to prevent, mitigate, and respond to climate change? And second, what legal consequences arise when states, by act or omission, breach those duties, particularly where the harm disproportionately affects other countries and communities, including future generations?

For many Global South states, ranging from small island developing states like Tuvalu and Mauritius to economies like India and Pakistan, this request was more than symbolic. Their submissions to the Court framed climate inaction as a breach of international law, grounded in principles of equity, differentiated responsibility, and reparation. The precise legal arguments varied, but most of them called for an international legal order that recognizes historical injustice, enforces climate obligations, and ensures redress for those most affected.

The opinion was released just days after Pakistan experienced another round of catastrophic flooding. This event echoed the country’s legal submission and highlighted the very harms the Global South sought to raise through international law.

This blog critically examines how the ICJ responded to those calls. It assesses the extent to which the Court’s opinion affirms the core legal demands articulated by Global South states, namely, (1) binding legal accountability, (2) reparations, and (3) the operationalisation of differentiated responsibilities, and where it fell short. The Court delivered a strong doctrinal endorsement of states’ climate obligations, but it ultimately avoided substantive innovation or enforcement. The result is a cautious but significant opinion: one that confirms the law’s relevance to climate justice, but leaves its transformative potential largely unrealised.

Binding Legal Accountability: Affirmed in Principle, Constrained in Practice

The first question posed to the ICJ asked about states’ international legal obligations with regard to climate change. From the submission of the majority of the Global South, the answer was clear: climate action is not a matter of policy discretion, but of legal duty. In this regard, the Court’s opinion offers a strong doctrinal endorsement. It affirms that states are bound by a range of obligations drawn from multiple legal sources:

• Treaty law, including the UN Framework Convention on Climate Change (UNFCCC), the Kyoto Protocol, and the Paris Agreement;
• Customary international law, including the no-harm rule and the duty to prevent significant transboundary harm; and
• Relevant human rights instruments, where climate impacts infringe upon rights to life, health, food, water, or cultural identity (paras. 172–173, 200–202, 268–270).

Crucially, the Court distinguishes between two types of obligations:

• Obligations of conduct, which require states to adopt mitigation and adaptation measures in line with scientific standards and evolving capabilities; and
• Obligations of result, which relate to actual outcomes, such as emissions reductions or preservation of ecological systems (paras. 203–208).

Both are recognised as legally binding. The Court rejects the idea that states can invoke national discretion or capacity constraints as a defence for non-compliance, emphasising that obligations must be construed and applied in good faith (para. 205).

This section of the opinion represents a partial vindication for many Global South states, for instance, Pakistan stressed in its submission that legally enforceable obligations, not voluntary pledges, are important for preserving the credibility........

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