On July 23, 2025, the International Court of Justice (ICJ) delivered a landmark Advisory Opinion on States’ climate change obligations — arguably the most consequential legal pronouncement of our time on climate justice.
The opinion responded to a historic request initiated by Vanuatu and supported by more than 130 nations under the auspices of the UN General Assembly, which asked the court two foundational questions: Firstly, “What are states’ legal obligations with respect to climate change?”
Secondly, “What are the legal consequences if they fail to meet these obligations?” The court confirmed that climate change is not merely a political-social-economic issue; it is a legal one, anchored in binding international obligations.
The court opined that states must act not only under the United Nations climate treaties (UNFCCC, Kyoto Protocol, Paris Agreement), but also in accordance with broader frameworks including human rights law, the law of the sea, and customary international law.
This broad legal foundation firmly rebuffs the idea that climate treaties are a closed regime (lex specialis), making it crystal- clear that climate obligations are deeply embedded in the global legal order.
One of the court’s most profound statements was its declaration that limiting global warming to 1.5°C is not aspirational but legally binding — enjoining states to revise their actions — and their inaction — through the lens of enforceable international norms. In a historic shift, the court confirmed that countries can be held accountable for failing to regulate fossil fuel production, consumption, subsidies and licensing.
The court further stated that this inertia can be construed as a wrongful act, attracting legal consequences — including restitution, compensation and satisfaction. The court opined that these measures may take the form of ecosystem restoration, rebuilding infrastructure, or direct monetary reparations to harmed nations, particularly vulnerable developing states.
Importantly, the court emphatically opined that the foregoing obligations apply universally (erga omnes). Even countries that have not ratified climate treaties — such as the United States — are still bound by customary international law to act.
Likewise, emerging economies such as China and India cannot hide behind broad “developing country” labels; current emissions and capacity to act now determine responsibility.
The court made a resounding call for enhanced action towards climate justice. It affirmed that forced displacement due to climate impacts triggers human rights protections, under the ‘non-refoulement’ principle. This development marks a crucial step in recognizing the legal status and rights of climate migrants, a group historically overlooked in global discourse.
Furthermore, the court emphasized that preparing, communicating and maintaining Nationally Determined Contributions (NDCs) is not enough; they must be ambitious, science-aligned and reflective of national capacities and historical emissions.
Failure to do so could now amount to a breach of international obligations. This Advisory Opinion is more than a legal document; it is a clarion call for ambition and accountability. It gives national courts, policymakers, and civil society a new legal foundation to press for stronger action.
For climate-vulnerable countries like Uganda and many global South nations, it offers legal recognition of the climate change brunt they are already bearing — and a pathway to equity and justice.
As the world gears up to COP30 in Belem, this development from the world’s highest court raises the stakes. It affirms that climate action is not optional; it is a legal duty. The age of unenforceable pledges is ending.
A new era — rooted in law, equity, and accountability — is finally here.
howardmwesigwa25@gmail.com
The writer is the team leader – Energy, Environment & Sustainability, Kalikumutima & Co. Advocates