What the ICJ says on nations' climate duties

And its implications for the Philippines amid the global climate crisis

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On July 23, 2025, the International Court of Justice (ICJ) issued a landmark Advisory Opinion (AO) on States' obligations in the context of climate change. The AO affirms that States must, "ensure the protection of the climate system and other parts of the environment from anthropogenic greenhouse gas emissions.

The ICJ recognized that, in addition to binding obligations under climate treaties such as the UNFCCC, Paris Agreement (PA), Kyoto Protocol, States also bear responsibilities under customary norms of international law. These include the duty to prevent significant harm to the environment and the duty to cooperate, both of which apply in the context of climate change.

Of particular note at this time is the binding nature of Article 4 of the PA, which requires Parties to "prepare, communicate, and maintain" Nationally Determined Contributions (NDCs). These NDCs outline the domestic mitigation measures that States intend to undertake. This emphasis on State NDC obligations is particularly timely given the ongoing 3rd cycle of NDC submissions, which countries are expected to turn in by September 2025.

In its Advisory Opinion, the ICJ affirmed that State obligations related to NDCs are legally binding. States are required to prepare, communicate, maintain, account for, and register their NDCs. These contributions must become more demanding over time, reflecting the highest possible ambition. States are also required to implement these NDCs effectively.