Chris Gasche

Associate Editor

Loyola University Chicago School of Law

The endangerment finding (EF) is the bedrock of environmental regulation within the United States. Founded on the basis of the the ruling in Massachusetts v. EPA, the Environmental Protection Agency (EPA) issued the “endangerment finding,” which declares two things. First, that greenhouse gases threaten the public health and welfare of current and future generations. Second, that the combined emissions of the greenhouse gases from motor vehicles contributes to overall greenhouse gas pollution, which in turn also threatens public health and welfare. This was the case. The EPA has repealed this finding. Now, the EPA lacks statutory authority under Section (a)(1) of the Clean Air Act (CAA),  to regulate greenhouse gas (GHG) emissions standards for motor vehicles and other industries. Now, the EPA is no longer legally required to regulate pollutants such as GHGs. There is no longer any federal legal foundation to regulate vehicle, industrial or power plant emissions.

Background for the decision

In making this decision, the EPA cites concerns that the EF exceeded the scope of the agency’s authority. By repealing the EF, the EPA says they are returning to the “best reading” of the CAA. According to a Harvard Law Review article, the EPA furthers three main arguments in support of the repeal. First, the EPA argues that under the CAA, “air pollution:” only applies to pollution with local or regional effects. Second, the EPA believes that GHG emissions from new motor vehicles do not “in any material way” affect public health and welfare. Third, the EPA believes that further regulation would be costly and pointless. The EPA also notes that by repealing the EF they are not eliminating the Agency’s ability to regulate general pollutants, just GHGs. Even still, this decision will have profound effects on environmental regulation within the United States. This is because the EF provided a scientific and legal basis for federal regulation of GHGs. Without it, federal climate policy is going to be significantly limited in its reach. Aside from the removal of emissions limits for consumer vehicles, the EF also paved the way for regulation of coal-fired and natural gas power plants. Since 2009, the academic support for the EF has only grown.

The EPA initially published the EF by utilizing assessments from several groups – specifically the U.S. Global Change Research Program, the Intergovernmental Panel on Climate Change (IPCC) and the U.S. National Research Council (USNRC). In 2018, a study in the journal Science found that there are numerous public health and safety risks associated with climate change and GHG pollution. This study reinforced the scientific basis for the EF. A major area of scientific progress is the finding that extreme weather events can be attributed to human-caused climate change. Additionally, the study notes that reduced nutritional security, effects on mental health, and an increased risk of population displacement and conflict are a natural outgrowth of climate change. Even with the backdrop of extensive research and documented harm from GHGs, the EPA no longer believes that GHG’s are a threat to human health and safety.

Immediate effects of the repeal

The removal of the EF will directly impact the automotive sector first. This is because the EF is tied to a particular section of the Clean Air Act which handles vehicle emissions. However, the EF also gave regulatory agencies the power to regulate other sectors as well such as emissions from power plants, buildings, and other forms of transport. Without it, GHG emissions in these sectors will go largely unregulated. These other sectors no longer have cognizable guidelines that they have to follow.

Notwithstanding climate change harms and the removal of the obligation to regulate these sectors, the repeal of the EF will have many other detrimental effects. The U.S. has long been a significant producer of CO2 emissions. Undoubtedly, this trend will continue following this latest action. It remains to be seen how the EPA and the Trump administration will attempt to regulate GHGs – or if they will attempt to regulate them at all. This move to repeal the EF is not surprising considering the Trump administration’s stance on environmental regulation. This comes after the US withdrew from the United Nations Framework Convention on Climate Change (UNFCCC) in early 2026. The withdrawal makes the U.S. the only nation that will not participate in climate discussions.

Possible recourse

In 2025, environmental organizations previously challenged an attempt by the EPA to repeal the EF. They are protesting the final action once again. Most notably, the Sierra Club issued a statement denouncing the repeal of the EF, citing concerns that it will severely increase climate change and could potentially open automobile manufacturers, power companies, and fossil fuel companies to large amounts of potential litigation. Previously, under the EF, these industries avoided common law federal enforcement because the courts argued that the claims are traditionally preempted under the CAA. Without the legal backing of the EF, the CAA may not longer preempt these kinds of claims.

At present, the options available to challenge the repeal are extremely limited. These organizations will need to pursue swift legal action in order to obtain court orders blocking or prohibiting the repeal from achieving its intended effects. These legal claims will almost certainly make their way to the Supreme Court. In the meantime, state governments will need to solidify and hopefully expand their existing regulations in order to prevent against the effects of missing federal regulation. Barring federal preemption of state law, states are not directly affected by this finding meaning that they still have the power to regulate GHGs on their own.