International Court of Justice (ICJ) advisory opinion marks a new era on Climate Accountability

Climate inaction is no longer just a political decision; it is a violation of legal commitments. On 23 July 2025, the International Court of Justice in The Hague made history with its long-awaited advisory opinion on States’ obligations to address climate change. Presented by the Court’s President, Judge Iwasawa Yuji, this landmark pronouncement under Article 65 of the ICJ Statute sets a new milestone in international environmental law.

????Background: From University of South Pacific to The Hague

The case stems from a campaign led by 27 students from the University of Pacific Island, fighting for their rights in the face of Climate Change. In 2019, they formed a youth-led grassroots movement called Pacific Island Students Fighting Climate Change (PISFCC) and began lobbying Pacific Islands Forum leaders to take the subject of climate change to the world's highest court. In 2021, the government of Vanuatu came forward to lead efforts to obtain an "advisory opinion" from the International Court of Justice. It worked to interact with the Pacific island community first, to form a "coalition of like-minded vulnerable countries". Vanuatu’s bold call for climate justice sparked a wave of global solidarity. Backed unanimously by the 18 Pacific Island Forum members, it went on to rally support across Europe, Asia, Africa, and Latin America. After three intense rounds of consultations, the moment came - the resolution landed before the UN General Assembly with an extraordinary 105 countries standing as co-sponsors. They announced their intent to seek clarity from the ICJ on States’ climate obligations.

⛔Need for Climate Action:

The need for climate action has never been more urgent. Rising global temperatures, extreme weather events, and rapidly depleting ecosystems are already threatening lives, livelihoods, and economies worldwide. Vulnerable communities, especially in small island nations, are on the frontlines, facing existential risks. At this critical hour, a decisive action is needed to cut emissions, protect natural systems, and uphold human rights, ensuring a safer and more just future for generations to come.

????UNGA to ICJ: What are States’ Duties on Climate Change?

The UN General Assembly saw the need to address the issue on 29 March 2023; following strong diplomatic efforts, and thereby, adopted a resolution requesting an advisory opinion on two questions:

Ø  What are the obligations of States under international law in relation to climate change mitigation, adaptation, and transboundary harm?

Ø  What are the legal consequences for States when they fail to meet these obligations?

Highlights of the Court’s Opinion:

????Right to a Clean, Healthy and Sustainable Environment: The Court affirmed that addressing climate change is necessary to protect human rights, which includes the right to food, shelter, health care as these rights cannot be realized without a safe environment.

????Duty to Prevent Environmental Harm: States must exercise stringent due diligence, and take reasonable measures by introducing robust national climate action plans in light of their development level, technological capacity, contributions to climate change, and vulnerability, to avoid causing severe harm to the climate system.

????️Obligation to Limit Greenhouse Gas Emissions: States are required to adopt measures consistent with the Paris Agreement target of limiting global warming to 1.5°C above pre-industrial levels, particularly given that global temperatures have already risen by 1.3°C.

????No Legal Silos: The Court rejected the argument made by some states including the United States, that climate treaties form a closed legal system (lex specialis). Lex specialis is a legal theory employed to determine if a more specific regulation can override a more general one, or if both rules can apply simultaneously. Instead, it held that climate treaties operate alongside other rules of international law, reinforcing States’ broader environmental and human rights obligations rather than excluding them.

????‍⚖️Principles Guiding State Conduct: The Court stressed that States with better resources must act in line with the CBDR-RC (common but differentiated responsibilities and respective capabilities) principle, and take preventive measures with higher standard of care, even amid scientific uncertainty, conduct science-based risk assessments, and consult in good faith with other states when activities may create transboundary risk or collective climate harm.

⚖️Consequences for Non-Compliance: Failure to meet obligations may give rise to legal responsibility. States shall be required to cease wrongful conduct, provide guarantees of non-repetition, and make full reparation where appropriate. The ICJ held that these obligations are ‘erga omnes’ - owed to the international community as a whole, which means that any state may invoke responsibility, not just injured states.

????Key Legal Frameworks Considered

The Court anchored its opinion in the UNFCCC, Kyoto Protocol, and Paris Agreement, calling them the “most directly relevant applicable law.”

It also drew from a broader set of treaties that shape global environmental responsibilities, including:

☑️The Ozone Layer Convention
☑️The Montreal Protocol and its Kigali Amendment
☑️The Convention on Biological Diversity
☑️The Convention to Combat Desertification

The Court relied on two complementary strands of international law:

• Environmental treaties that impose obligations to protect the global commons and preserve the environment for present and future generations.
• Human rights treaties, under which States are obliged to guarantee the enjoyment of fundamental rights that depend on a clean and sustainable environment.

????Significance
This landmark opinion lays down a clear path to hold States accountable, firmly linking human rights with climate action. It marks a powerful step forward for global climate justice, especially for small island nations and vulnerable communities on the frontlines of the climate crisis.