In a unanimous decision on July 23, 2025, the fifteen judges on the United Nations’ International Court of Justice (“ICJ”), also known as the “World Court,” concluded that the production and consumption of fossil fuels “may constitute an internationally wrongful act attributable to that state.” The opinion also stated that limiting global warming to 1.5C should be considered the “primary temperature goal” for nations and, to achieve it, they are obliged to make “adequate contributions.”
By way of background, this case was initiated by a group of 27 students from the University of the South Pacific in Fiji in 2019, sponsored by the government of Vanuatu in 2021, and supported by 105 sponsor countries. During a two-week hearing held in December 2024 at the request of the U.N. General Assembly, the ICJ was asked to consider: (1) what obligations countries have under existing international treaties to protect the climate from greenhouse gases; and (2) what the consequences are if they cause climate-related damage.
During the hearing, countries who produce large amounts of fossil fuels argued that treaties, such as the Paris Climate Agreement, the Kyoto Protocol, and the United Nations Framework Convention on Climate Change, adequately address the impacts of climate change. However, other countries argued that these treaties, alone, are insufficient and unenforceable.
The ICJ ultimately held that every country has an obligation to “prevent significant harm to the environment.” Notably, the ICJ’s opinion went even further and stated that each country’s obligations extend to the behavior of companies under their respective jurisdictions.
Moreover, the ICJ also opened the door for countries to sue each other for damages caused by greenhouse gas emissions. In particular, the ICJ found that “while climate change is caused by cumulative greenhouse gas emissions, it is scientifically possible to determine each state’s total contribution to global emissions.”
Notably, disputes between countries over international treaties are typically settled through negotiations rather than through lawsuits. Therefore, it remains to be seen how the ICJ’s opinion will impact these negotiations going forward or whether it will lead to an increased number of lawsuits that are filed in the future. Although the ICJ’s decision is not legally binding and is only an advisory opinion, it will likely be cited in court cases throughout the world and could even become a powerful strategic tool to hold countries accountable for their previous climate change pledges and obligations.