Removing EPA's endangerment finding – the foundation of US climate policy – is complex and may lead to unexpected outcomes

The Endangerment Finding and Its Legal Significance

The United States has long relied on a foundational document known as the endangerment finding, which asserts that greenhouse gas emissions pose a threat to public health and welfare. This determination has served as the legal basis for numerous climate regulations. However, the Trump administration is now attempting to dismantle this critical framework.

On July 29, 2025, EPA Administrator Lee Zeldin announced plans to publish a rule aimed at rescinding the endangerment finding, with a 45-day period for public comment. A draft of the proposal suggests that the EPA lacked authority to issue the original endangerment finding in 2009 and that vehicle emissions are not significant contributors to global greenhouse gas emissions. It also claims that the costs of regulations outweigh their benefits. These arguments are seen as legally and factually weak, and they will require thorough examination once the proposal is officially published in the Federal Register.

Revoking the endangerment finding is not a straightforward process. If finalized, it could lead to a wave of lawsuits. Additionally, it may have unintended consequences for the industries that the Trump administration aims to support.

Origins and Legal Limits of the Endangerment Finding

The endangerment finding originated from a pivotal Supreme Court decision in 2007, Massachusetts v. EPA. In this case, the Court ruled that six greenhouse gases qualify as pollutants under the Clean Air Act and that the EPA must determine if they pose a danger to public health or welfare. The Court emphasized that the endangerment finding was a scientific determination, rejecting policy arguments from the George W. Bush administration that favored nonregulatory approaches to reduce emissions.

Following this ruling, the EPA issued the endangerment finding, which was later upheld in 2012 by the U.S. Court of Appeals for the D.C. Circuit in Coalition for Responsible Regulation v. EPA. The court found that the scientific evidence supporting the endangerment finding was substantial. The Supreme Court declined to review the decision, and the finding was updated and confirmed by the EPA in 2015 and 2016.

Scientific Basis and Challenges

Today, the scientific foundation for the endangerment finding is stronger than ever. The Intergovernmental Panel on Climate Change’s latest assessment report confirms that human activities are causing climate warming. The National Climate Assessment released in 2023 highlights that the effects of climate change are already widespread and worsening across the U.S.

During President Donald Trump’s first term, then-EPA Administrator Scott Pruitt considered repealing the endangerment finding but ultimately decided against it. He even used it in proposing the Affordable Clean Energy Rule to replace Obama’s Clean Power Plan.

Zeldin's Cost Argument

Zeldin previously outlined his arguments for rescinding the endangerment finding in a news release on March 12. One of his main points was that the 2009 finding did not consider costs. However, this argument was rejected by the D.C. Circuit Court in Coalition for Responsible Regulation v. EPA. Cost considerations become relevant only after the endangerment finding has been established. Furthermore, in a 2001 decision, the Supreme Court in Whitman v. American Trucking Associations ruled that the EPA cannot factor in cost when setting air quality standards.

Consequences of Revoking the Endangerment Finding

Even if the EPA successfully revokes the endangerment finding, it does not automatically repeal all rules that depend on it. Each rule would need to go through separate rulemaking processes, which could take months. The agency would also face numerous lawsuits.

Zeldin could choose to stop enforcing existing rules. However, such a blanket policy might be challenged as arbitrary and capricious. Regulated industries could also face risks if they delay compliance, only to find that the endangerment finding and climate laws remain in place.

Potential Backfire for the Fossil Fuel Industry

Repealing the endangerment finding could backfire on the fossil fuel industry. States and cities have filed lawsuits against major oil companies, with the industry arguing that these cases are preempted by federal law. In AEP v. Connecticut (2011), the Supreme Court ruled that the Clean Air Act "displaced" federal common law, barring state claims related to climate change damages.

If the endangerment finding is repealed, there may be no basis for federal preemption, allowing state lawsuits to proceed. Industry lawyers have warned the EPA about this and urged it to focus on changing individual regulations instead. The industry may even seek congressional immunity from climate lawsuits.

Legal Challenges Ahead

Zeldin may count on the conservative Supreme Court to support his actions, but he may be disappointed. In 2024, the Court overturned the Chevron doctrine, which required courts to defer to agencies’ interpretations of ambiguous laws. This means Zeldin’s reinterpretation of the statute is not entitled to deference. Additionally, he cannot rely on the Court overturning its Massachusetts v. EPA ruling to disregard science for policy reasons.

This article originally appeared on The Conversation, a nonprofit, independent news organization providing factual analysis to help readers understand complex issues. It was written by Patrick Parenteau, a law professor at Vermont Law & Graduate School.