Significant opinions from three international judicial bodies over the past year might be shifting the legal landscape on climate change.
A new analysis from the Micronesian Center for Sustainable Transport (MCST) examines what these opinions mean for international shipping and the negotiations now underway at the International Maritime Organization (IMO).
What the opinions say
The International Tribunal for the Law of the Sea (ITLOS) Advisory Opinion on Climate Change classified greenhouse gas emissions as marine pollution under the UN Convention on the Law of the Sea.The opinion goes onto to argue there is a binding duty on states to do exercise diligence to prevent harm to the oceans, including carrying out environmental impact assessments and acting on the best available science. The opinion also highlighted the special vulnerability of Small Island Developing States (SIDS).
The Inter-American Court of Human Rights (IACHR) Advisory Opinion on the Scope of State Obligations Related to Climate Change connected climate change directly to human rights. It found that failure to act on emissions could amount to a violation of rights guaranteed under the American Convention on Human Rights. Crucially, it made clear that obligations extend beyond borders: states must take measures that prevent harm to people outside their own territory, with a priority on protecting Indigenous peoples and SIDS.
The International Court of Justice (ICJ) Advisory Opinion on Obligations of States in Respect of Climate Change offered the most comprehensive opinion. It identified obligations under customary international law, and human rights treaties to protect the climate system, applying principles like equity, precaution, and intergenerational justice. The court also made it clear that “equity” goes beyond the categories used in UN climate negotiations, and applies as a general legal principle. They make clear that obligations are “erga omnes”- owed to the international community as a whole – and that failure to act is not simply regrettable, but unlawful.
Reflecting on the court’s opinion, Vanuatu Climate Change, Energy and Environment Minister Ralph Regenvanu said the court made it clear that “action on climate change by states, whether according to the Climate Change Treaties, the Climate Change Convention, the Paris Agreement, or all international customary law, is a legal obligation.” He added that the opinion “removed a lot of excuses from high-emitting states and gave vulnerable countries more leverage in their discussions.”
Together, these opinions bring much-needed clarity to fragmented climate law. They affirm that climate obligations are owed to the international community as a whole. They emphasize systemic integration across treaties, meaning that international law must be read and applied in a joined-up way.
They also underscore procedural duties such as transparency and inclusivity. For vulnerable states, particularly SIDS, this matters. These opinions empower them by framing climate inaction as a breach of due diligence, giving their demands in negotiations a stronger foundation.
What it means for shipping
A central issue in the upcoming Net Zero Framework is equity. In the IMO the Net Zero Framework is the phasing out greenhouse gas emissions from international shipping as soon as possible, while ensuring the transition is just and equitable. The creation of a Net Zero Fund suggests recognition of the need to support vulnerable countries, but the design carries risks.
If revenue is channelled primarily into decarbonisation projects in developed markets, SIDS and the wider developing world may be left without the means to transition their own shipping sectors.
The advisory opinions reinforce that such outcomes would fall short of international obligations. Fairness must be measured not just by ambition in emissions cuts, but also by the distribution of resources to those who face the greatest risks and bear the least responsibility.
The opinions also highlight transparency and inclusivity as legal duties. Decisions on climate action must involve those most affected. For the IMO, this means ensuring that SIDS and least developed countries are not sidelined in closed negotiations but are able to participate fully in shaping outcomes.
The consensus model of decision-making at the IMO cannot justify outcomes that ignore the vulnerabilities of small states. Systemic integration, as underscored by the ICJ, demands that the IMO’s processes meet broader standards of cooperation and fairness in international law.
Taken together, the opinions raise the standard for ambition, equity, and inclusivity in shipping governance.
Previously IMO members have been able to operate in a silo to international climate agreements, although the 2015 Paris Agreement on climate change is part of its Strategy on Reduction of GHG Emissions from Ships. However binding action on achieving the climate goals in the strategy fell short at its April meeting. Now, with the ICJ ruling in particular the IMO cannot treat climate ambition, equity, or inclusivity as optional. They are legal requirements. Anything less risks undermining the credibility of the Net Zero Framework and breaching international obligations that have now been confirmed at the highest legal level.Future IMO efforts must prioritize SIDS to avoid breaches, fostering a holistic climate regime.
A more detailed analysis of these advisory opinions and their implications for shipping will be available on the MCST website.
Source: Micronesian Center for Sustainable Transport
