Explained: The climate change case in the International Court of Justice

On March 29, 2023, Small Island Developing States (SIDS) took a historic climate case to the International Court of Justice (ICJ), seeking a ruling on states' legal duties to combat climate change. With unprecedented global participation, this case could reshape climate law and accountability worldwide. 

Introduction

What is the International Court of Justice (ICJ), and what role does it play?

The International Court of Justice (ICJ) is the principal judicial organ of the United Nations (UN), established in 1945 and headquartered in The Hague, Netherlands. It serves two primary functions:

1. Settling disputes between states on matters of international law (legally binding rulings).
2. Providing advisory opinions on legal questions referred by UN bodies and agencies (non-binding but highly influential).

The ICJ plays a critical role in shaping international legal norms by interpreting treaties, clarifying state obligations, and reinforcing legal principles that govern state behavior. While it does not have enforcement power, its rulings and advisory opinions are often used as legal precedents in international negotiations, domestic courts, and future treaties.

What is an advisory opinion, and who is authorized to request one?

An advisory opinion is a formal legal interpretation issued by the ICJ at the request of UN bodies or international organizations. Unlike rulings in disputes between states, advisory opinions are not legally binding, but they hold significant weight in shaping international law and policy.

The following UN bodies are authorized to request an advisory opinion:

• The United Nations General Assembly (UNGA)
• The United Nations Security Council (UNSC)
• Specialized UN agencies, such as the World Health Organization (WHO), United Nations Educational, Scientific and Cultural Organization (UNESCO), and International Monetary Fund (IMF)

What are Small Island Developing States (SIDS), and why are they at the center of this case?

Small Island Developing States (SIDS) are 39 states and 18 associate members recognized by the UN as particularly vulnerable to economic, social, and environmental challenges. These states are spread across:

• The Caribbean
• The Pacific
• The Atlantic, Indian Ocean, and South China Sea (AIS)

Though SIDS represents less than 1% of the world’s population (approx. 65 million people), they face some of the most severe consequences of climate change, including:

• Rising sea levels are threatening to submerge entire nations.
• Extreme weather events, such as hurricanes and cyclones that devastate infrastructure.
• Loss of biodiversity and coral reefs, affecting tourism and fisheries, which are critical to their economies.
• Climate-induced displacement, forcing populations to migrate, raising concerns over sovereignty and citizenship.

Who initiated this case, and how did it reach the ICJ?

The legal push for this case began with Pacific Island Students Fighting Climate Change (PISFCC). In 2019, a group of 27 students from the University of the South Pacific came together to begin a campaign to persuade the leaders of the Pacific Islands Forum to take the issue of climate change and human rights to the International Court of Justice, urging their governments to seek an ICJ advisory opinion on climate change obligations under international law. In September 2021, Vanuatu, along with 18 other nations, drafted a UN General Assembly (UNGA) resolution requesting the ICJ’s opinion on states’ legal duties regarding climate change.

The Case at the ICJ

What is the primary legal issue in this case?

This case seeks to determine:

• Whether states have a legal obligation under international law to prevent climate harm?
• What legal consequences should states face if they fail to meet their obligations?

SIDS argue that climate change is not just an environmental issue but a matter of legal responsibility, as states have a duty under international law to protect vulnerable populations, which the treaties alone do not meticulously specify.

Which parties are involved in this case?

• Petitioning States (SIDS): Small Island States like Vanuatu, Tuvalu, and the Maldives.
• Supporting Nations: A total of 132 countries, mostly from the Global South, advocating for stronger climate commitments, including countries like Vietnam, Timor-Leste, Costa Rica etc.
• Opposing States: Major polluters like the United States, China, and Saudi Arabia argue that climate obligations should remain within existing treaties.
• International Organizations: Entities such as the International Union for Conservation of Nature (IUCN) and the United Nations.
• Legal Experts & Indigenous Groups: Advocating for stronger legal standards to hold nations accountable.

Timeline of the Case

The Significance of the Case

Why is this case considered a historic moment in international law?

This case represents the first time in history that the ICJ has been asked to define states' legal responsibilities regarding climate change. It has drawn participation from 96 countries and 11 international organizations, making it the largest climate-related legal proceeding ever held.

The ruling could fundamentally reshape climate accountability, influencing future treaties, legal actions, and international relations.

Has there been a similar case before?

In 2024, the International Tribunal for the Law of the Sea (ITLOS) ruled that states must control greenhouse gas emissions under maritime laws. However, the ICJ case is far broader, addressing global legal responsibilities beyond maritime concerns.

What is the stance of major global powers?

• United States & China: Oppose expanding legal climate obligations beyond the Paris Agreement.
• United Kingdom: Have remained neutral but are closely monitoring the case.

How could this ruling affect India specifically?

India is both a major emitter of greenhouse gases and highly vulnerable to climate change, facing rising temperatures, water shortages, and extreme weather events. A strong ICJ ruling could:

1. Push India to strengthen its climate policies, particularly in energy and emissions reduction.
2. Support India’s stance in climate negotiations, as India has argued that developed nations should bear greater responsibility for historical emissions.
3. Impact on Indian industries, particularly in coal, manufacturing, and exports, if new climate regulations are introduced.

What impact can an ICJ advisory opinion have on global climate governance?

While an advisory opinion does not impose direct legal obligations, it can:

• Influence the development of new international treaties by clarifying legal principles.
• Strengthen climate litigation efforts, allowing affected nations or communities to file lawsuits against major polluters.
• Put diplomatic pressure on major economies to adopt stronger environmental regulations.
• Encourage stronger national and regional policies to align with international legal principles on climate action.

Conclusion

This ICJ case is not just a legal debate—it is a turning point in international climate governance. If the ICJ delivers a strong advisory opinion, it could:

• Set the foundation for future climate lawsuits.
• Compel stronger international treaties.
• Hold major polluting nations accountable for climate harm.

For Small Island Developing States, this case is about survival. For the rest of the world, it is a clear signal that climate inaction may soon come with serious legal consequences. The ICJ’s decision will be one of the most significant legal milestones in climate justice history.

Homita Ganguly is a final-year student at Christ (Deemed to be University), pursuing BSc in Economics and Analytics. She is currently working as a Research Analyst Intern at The Analysis.