Author: Payal Kumari

Court: International Court of Justice (ICJ)

Date of the Judgment: 23 July 2025

Case Type: Advisory Opinion (non-binding but authoritative)

Bench: The full bench of 15 judges of the ICJ participated in issuing this unanimous advisory opinion.

Relevant Provisions:

United Nations Framework Convention on Climate Change (UNFCCC)

Paris Agreement (specifically the 1.5°C temperature goal)

Customary International Law principles (due diligence, no significant harm, cooperation)

Human rights obligations related to environmental protection

United Nations General Assembly resolution 77/276 requesting the advisory opinion

Introduction 

The International Court of Justice (ICJ) asked for an Advisory Opinion on the Obligations of States in Respect of Climate Change, delivered in July 2025, which became an international landmark judgement. It was requested by Small Island Developing States, which were facing a threat because of climate change. So they asked to clarify the duties of the state under international law so that they can fight the crisis. So the judgment came, which affirms that the obligations are beyond political agreements, emphasising the urgency of collective action. The opinion integrates scientific evidence and legal principles, which shows the importance of protecting human rights and vulnerable communities. And it also helps in enhancing accountability and cooperation in global climate governance.

Brief Facts 

Small Island Developing States, led by Vanuatu, asked for an advisory opinion from the ICJ to clarify States’ legal obligations to address threats due to climate change. Apart from them, 97 States and 11 organisations also participated in this, which shows the importance of dealing with the issue due to climate change. The main issues involved greenhouse gas mitigation, climate finance, technology transfer, and adaptation to climate-induced harm. The ICJ examined scientific evidence and said that States have binding international obligations under customary and treaty law, emphasising “the principle of common but differentiated responsibilities.” It also called on States to enforce effective climate policies.

 Issue Involved 

• What are the legal obligations of States under international law to address and prevent climate change harm?
• Are these obligations binding and enforceable beyond existing treaties?
• What responsibilities do States hold towards vulnerable nations and future generations?

Petitioner’s Argument 

The Small Island States argued that States have binding legal obligations under international law to prevent climate change harm, beyond voluntary treaty commitments. They said that major polluting States must be held accountable for failing to reduce emissions and support adaptation in vulnerable countries. They also sought clarity on liability and reparations for climate damages caused by non-compliance.

Respondent’s Argument 

Several developed countries, including the US, Germany, and Saudi Arabia, said that existing international treaties sufficiently regulate climate change obligations and that no new binding duties should be imposed. They also assert the ICJ’s jurisdiction for advisory opinions with political and scientific complexity.

Judgement 

The ICJ, in its advisory opinion delivered on 23 July 2025, where they said- 

• States have legally binding obligations to address climate change under customary international law and treaty commitments.
• The Court interpreted the provisions of the UNFCCC and Paris Agreement as establishing both procedural and substantive obligations and said States must take ambitious mitigation actions to limit the global temperature rise to well below 2°C, and preferably 1.5°C, above pre-industrial levels. 
•  The ICJ emphasised the principle of “common but differentiated responsibilities,” where it said that Developing States also have obligations but are afforded compared to developed States, as the developed states bear greater duties due to their greater capabilities.
• The Court reaffirmed the principle of due diligence, requiring States to act preventively and with vigilance to avoid significant transboundary harm to other States, especially vulnerable ones.
• The Court further clarified that States’ obligations include protecting human rights such as the rights to life, health, and culture.
• The advisory opinion underscored States’ responsibilities towards future generations. 

Ratio Decidendi 

• States Have Binding Legal Obligations under International Law to Address Climate Change

This means that the duty to mitigate and adapt to climate change is not just political or moral but legally enforceable under international law, which includes customary law and treaties like the Paris Agreement.

• 1.5°C Temperature Target is a Legally Binding Benchmark

The ICJ elevated the Paris Agreement’s 1.5°C goal from a political aspiration to a concrete legal obligation guiding the scope and ambition of each State’s climate actions. So that each and every state can get clarification of their duties.

• Discretion in Setting Nationally Determined Contributions (NDCs) Is Limited

It says that States cannot set emission reduction plans arbitrarily. They must exercise due diligence to ensure that collective NDCs achieve the 1.5°C target.

• Principle of Common But Differentiated Responsibilities Applies

Developed countries bear a higher standard of care and responsibility due to historic emissions and greater capabilities, while developing states have obligations aligned with their capacities, which are comparatively lower than a developed state’s care and responsibilities.

• Non-Compliance May Lead to International Legal Responsibility and Liability

Breaches of these duties can constitute internationally wrongful acts, which will open pathways for reparations or legal claims.

• Human Rights Integration

The rights to life, health, and cultural heritage are linked to climate protection, making States’ climate obligations also duties to uphold these fundamental rights because it’s necessary.

Analysis 

These are the analyses-

1. While prior agreements like the Paris Agreement set political ambitions, in this case, the Court confirmed that these goals also carry legal weight.

2. In this case, they recognised the substantive duties alongside procedural obligations which elevate States’ responsibilities. 

3. The principle of due diligence, also reaffirmed, where the Court ensures that States must not only legislate but enforce actions that prevent harmful climate effects on others, especially vulnerable communities.

4. It made a binding commitment to States to respect fundamental rights tied to a stable climate system.

5. It also acknowledged differentiated responsibilities of developed states and developing states, ensuring a balance of fairness and practicality.

6. The opinion also helps in guiding national courts, policymakers, and global institutions towards a coherent climate.

7. While the advisory opinion itself is not legally binding, it heavily influences State practice, negotiations, and liability claims worldwide.

8. The ruling encourages robust environmental impact assessments, accountability, and transparency in climate governance.

9. This decision encourages States to raise climate ambition and promotes legal mechanisms to hold them accountable.

10. It marks a turning point in the recognition of climate change as a matter of international law.

Final Decision 

These are the final decisions of this case-

1. States have clear binding obligations under international law to mitigate climate change.

2. Developed States bear greater responsibility compared to developing states due to historic emissions and capacity.

3. States must prevent significant transboundary environmental harm.

4. Human rights linked to environmental protection must be safeguarded.

5. Obligations extend to protecting future generations.

6. Failure to meet duties can lead to international responsibility and potential amendment.

7. Fossil fuel production must be phased out and policies aligned to the 1.5°C target.

8. Enhanced transparency, reporting, and cooperation are essential.

9. The ruling provides a legal foundation for climate justice and litigation globally.

10. The opinion supports global efforts for sustainable development and environmental protection.