Legal anchor in climate opinion

By turning due diligence into a concrete, evolving, and enforceable standard, the ICJ has given states, courts, and communities a workable tool to assess climate conduct

- SHASHANK PANDEY

ON WEDNESDAY, THE International Court of Justice (ICJ) delivered its advisory opinion in response to the UN General Assembly's request to clarify the obligations of states under international law with respect to the climate system.

While the opinion addresses a wide range of issues, ranging from human rights to rising sea levels, the court identifies due diligence as the key legal standard that determines whether states have met their obligations to prevent harm from greenhouse gas (GHG) emissions.

In the complex architecture of treaty law, customary obligations, and evolving scientific knowledge, the concept of due diligence provides the clearest, enforceable test of lawful state conduct.

Here, the focus will be on the due diligence standard because it is not only central to the court's reasoning but also the most usable legal tool going forward to assess climate accountability.

Due diligence as a threshold for responsibility

The ICJ affirms that due diligence is a duty of conduct, not of result (para. 136).

In climate terms, it means a state must do everything "reasonably available" within its means to avoid causing significant environmental harm, particularly from GHG emissions (para. 272-273).

Importantly, the ICJ characterises due diligence as stringent in the climate context (para. 280), reflecting the scale and urgency of the crisis.

Due diligence is not generic.

It must be assessed in concreto, considering a state's specific circumstances but with no room for inaction.