One astoundingly bright development stands out, upon review of the international scene during 2025.
If nurtured and utilized in the new year, moreover, it could help turn the tide with respect to our ruptured climate. But the required nurturing will be tough, involving as it does a return to (or rise of) the rule of law in major emitting nations.
I speak here of the International Court of Justice’s remarkably strong Advisory Opinion, concerning “The Obligations of States in Respect of Climate Change.” [We provide it below.]
Released on July 23, 2025, at the Peace Palace in The Hague, the ICJ, known also as the World Court, determined that international law imposes on every nation affirmative legal duties to protect the climate system, and that those duties extend beyond merely formal compliance with specific terms of treaties into which nations have voluntarily entered.
For background, CPR Initiative supporters can review certain of my blog entries in late 2024, including: What’s International Law Got To Do With It? (November 25, 2024) and A Small Flame, Burning Bright (December 3, 2024). See also our video-stream reports from The Hague of December 9, 2024 (also featuring climate experts Jame E. Hansen, Eelco Rohling, Appy A. Sluijs, and Ingrid Robeyns) and December 14, 2024 (summarizing the ICJ hearings, including critical questions raised at its close by four of the justices).
The Court certainly agreed with most of the formal parties to the case that the terms of major international climate covenants delineate many of the States’ central relevant obligations. Those covenants include the 1992 United Nations Framework Convention on Climate Change and the 2015 Paris Agreement to the UNFCCC.
With respect to the UNFCCC, the Court identified as key obligations the overriding duty to mitigate dangerous climate change by limiting anthropogenic sources of GHG emissions and taking action to preserve and enhance sinks and reservoirs of GHGs.
Turning to the Paris Agreement, the Court observed that its temperature targets “concretized” the UNFCCC’s more general goals — although the Court did not discuss those targets’ continuing utility in the circumstance that global averaged temperatures increasingly overtop the 1.5oC aspirational threshold. (See, e.g., Hansen et.al., Global Temperature in 2025, 2026, 2027).
The Court also discussed the Paris Agreement’s requirement that nations develop and submit increasingly stringent plans for domestic GHG mitigation, that is, “Nationally Determined Contributions.” These amount to obligations of conduct, not result, and for that reason, according to the Court, “parties are required to act with due diligence in taking necessary measures to achieve the objectives set out in their successive NDCs.”
Beyond specified terms found in climate treaties and covenants, the Court determined that nations are obliged to adhere to central principles of customary international law, including the duty of States (a) to prevent significant harm to the environment and (b) to co-operate for the protection of the environment. Moreover, the Court determined that these duties attach irrespective of any State’s continuing participation inm or acceptance, the terms of any of the climate treaties.
The duties of international co-operation and to prevent significant harm apply to each State
irrespective of its continuing participation in any of the climate change treaties.
The duty to prevent significant harm to the climate system and other features of the environment requires each State to act with due diligence, including use of “all the means at its disposal [] to avoid activities which take place in its territory, or in any area under its jurisdiction, causing significant damage to the environment of another State.”
This in turn requires, according to the Court, that every State “put in place a national system, including legislation, administrative procedures and an enforcement mechanism necessary to regulate the activities in question, and . . . exercise adequate vigilance to make such a system function efficiently, with a view to achieving the intended objective.”
Importantly, the Court specified that such rules and measures must include “regulatory mitigation mechanisms that are designed to achieve the deep, rapid, and sustained reductions of GHG emissions that are necessary for the prevention of significant harm to the climate system. [] These rules and measures must regulate the conduct of public and private operators within the States’ jurisdiction or control and be accompanied by effective enforcement and monitoring mechanisms to ensure their implementation.”
These pointed admonitions by the Court were issued in the midst of remarkable efforts by the Trump II government to cut sharply in the other direction, that is, by pressing for the dismantlement of our nation’s existing regulatory GHG mitigation mechanisms. I am sure that the Court was well aware of that juxtaposition and, for that reason, I think, saw fit to go the extra mile to describe the failure of a State to take meaningful action as an “internationally wrongful act.”
Those wrongful acts, moreover, include those of omission as well as those of commission. Accordingly the Court specified, in partial response to a question one of its justices had raised at the close of the fortnight of oral argument, that “[f]ailure of a State to take appropriate action to protect the climate system from GHG emissions — including through fossil fuel production, fossil fuel consumption, the granting of fossil fuel exploration licenses or the provision of fossil fuel subsidies — may constitute an internationally wrongful act which is attributable to that State.”
Failure to protect the climate system from [fossil fuel] GHG emissions
may constitute an internationally wrongful act.
In the above, I’ve touched upon some of the ICJ Opinion’s powerful determinations and admonitions. They can guide, if not govern, renewed climate action on both the international and domestic fronts as soon as the new year — if, or when, with all of our help, the rule of law regains its footing.
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