ICJ’s Landmark Opinion Affirms States’ Legal Duties to Combat Climate Change

In a momentous legal development hailed by environmental defenders, human rights advocates, and small island nations, the International Court of Justice (ICJ) has delivered an authoritative advisory opinion affirming that States have clear and enforceable obligations under international law to combat climate change. The ruling, delivered on Wednesday, is already being described as a “sweeping victory” for global climate justice by UN High Commissioner for Human Rights Volker Türk.

The opinion not only underscores the human rights dimensions of the climate crisis but also sets a powerful precedent for holding States legally accountable for greenhouse gas emissions and related environmental degradation.

A Victory Rooted in Pacific Island Youth Activism

High Commissioner Türk credited the “inspiring movement” led by students from Pacific Island nations—particularly Vanuatu—as instrumental in securing this historic legal milestone. The initiative began with youth-led advocacy in the Pacific, culminating in a request by Vanuatu and other island states at the UN General Assembly in 2023 to seek the Court’s opinion on the legal obligations of States in relation to climate change.

“The Opinion is a testament to the power of grassroots mobilization,” said Türk. “It affirms that climate harms are actionable under international law, and that States must urgently change course.”

Human Rights at the Core of Climate Responsibilities

In its opinion, the ICJ stated unequivocally that international human rights law applies directly to climate change. The Court affirmed that the right to life, and the right to a clean, healthy, and sustainable environment, are among the most affected by climate inaction.

This builds upon the UN Human Rights Council’s 2021 recognition of the right to a healthy environment as a fundamental human right. The ICJ’s ruling makes it clear that environmental degradation caused by unchecked emissions and the failure to mitigate climate change can constitute violations of these rights.

In its analysis, the Court referred to documentation and interpretations from multiple UN human rights mechanisms, including the UN Human Rights Office and regional courts, highlighting a consistent international understanding of climate-linked human rights obligations.

Legal Duties and Consequences for States

The ICJ emphasized that States have a duty to prevent activities within their jurisdiction or control from causing significant harm to the climate system or the broader environment. This includes:

• Limiting fossil fuel production and consumption,

• Ending fossil fuel subsidies,

• Avoiding the issuance of exploration and drilling licences, and

• Imposing regulations on private sector emissions.

Importantly, the Court ruled that failure to act on climate change can constitute an internationally wrongful act, potentially triggering legal consequences under customary international law. These may include:

• Cessation of harmful activities,

• Assurances of non-repetition,

• Reparations to affected communities or States, and

• Enforcement of effective regulatory frameworks.

This sets a precedent that could bolster climate litigation worldwide, empowering courts and activists to demand accountability from governments and fossil fuel corporations alike.

A Call to Action for Transformative Change

“The Court has provided a roadmap for people and governments to seek the transformative change and accountability we need in the fight against climate change,” Türk said.

He called on all States to reflect the ICJ’s legal findings in their national and international climate strategies. This includes the formulation of new nationally determined contributions (NDCs) due in September under the Paris Agreement, and the upcoming negotiations at COP30 in Brazil this November.

The High Commissioner also urged governments to implement climate policies that prioritize human rights, social equity, and reparations for those most affected—particularly Indigenous peoples, youth, coastal and island communities, and vulnerable populations.

“My Office is committed to working with States, businesses, civil society and people everywhere to advance climate solutions that take into account human rights,” Türk affirmed.

Implications for Climate Justice and Global Accountability

The ICJ's ruling adds to a growing body of legal norms reinforcing the intersection between environmental protection and human rights. It echoes similar rulings in domestic and regional courts—such as the 2019 Urgenda decision in the Netherlands and the European Court of Human Rights’ climate ruling earlier this year.

By framing climate change not only as an environmental issue but also as a matter of human dignity and legal duty, the ICJ has delivered a compelling message: inaction is not just immoral—it is unlawful.

As nations prepare for a decisive phase of international climate negotiations and implementation, the ICJ’s opinion offers a new foundation for demanding bolder, rights-based climate action—and for ensuring that the voices of the most vulnerable are central to the global climate response.