Coalition challenges MATS Rule repeal as unlawful
Summary
Rhode Island AG Neronha joined 21 states and local governments in filing a federal lawsuit challenging the Trump Administration's repeal of the 2024 Mercury and Air Toxics Standards (MATS) Rule. The coalition argues the EPA failed to provide a reasoned basis for reverting to outdated emissions standards for coal- and oil-fired power plants that limit mercury, arsenic, lead, and acid gas emissions. The lawsuit seeks judicial reversal of the rollback.
What changed
The coalition of 21 states and local governments filed a federal lawsuit challenging the EPA's repeal of the 2024 Mercury and Air Toxics Standards, which had updated limits on toxic emissions including mercury, arsenic, lead, and acid gases from coal- and oil-fired power plants. The coalition argues the repeal is unlawful because the EPA failed to provide a reasoned justification and did not adequately consider developments in pollution control technologies. The filing identifies mercury as a potent neurotoxin particularly harmful to pregnant women and children, with exposure risks including developmental harms, neurological disorders, cardiovascular disease, and diabetes. Mercury contamination from power plants also threatens waterways and commercial fishing economies.
Energy companies operating coal- and oil-fired power plants face potential regulatory uncertainty as this legal challenge proceeds. The coalition is seeking court determination that the repeal is unlawful and must be reversed, which could restore the 2024 MATS standards. Regulated entities should monitor this litigation as a favorable outcome could reinstate stricter emission limits. The case will proceed through federal courts and may ultimately determine whether the MATS rollback stands or must be reexamined by the EPA.
Source document (simplified)
Attorney General Neronha, coalition sue Trump Administration for rolling back limits on toxic air pollutants
Published on Tuesday, March 31, 2026
Attorney General Peter F. Neronha today joined a coalition of 21 states and local governments in filing a lawsuit challenging the Trump Administration’s repeal of the 2024 Mercury and Air Toxics Standards (MATS) Rule and return to outdated standards that harm the environment and public health.
The MATS Rule implements nationwide standards that limit emissions of toxic air pollutants from coal- and oil-fired power plants, including mercury, arsenic, lead and other toxic metals, in addition to acid gases, such as hydrogen chloride and formaldehyde. In 2024, following significant developments in the technologies used to control pollution, the Environmental Protection Agency (EPA) updated the standards for emissions of these hazardous air pollutants from power plants. Last month, the Trump administration rolled back the updated standard, allowing for more of these dangerous emissions to be released into the air.
“Public health and safety should be the top priority of any government,” said Attorney General Neronha. “Here, we have the Trump Administration once again acting recklessly and without good reason in rolling back important emissions standards that help mitigate the potentially disastrous health effects of toxic air pollutants associated with power plants like mercury and arsenic. Americans should be able to trust that their government is working to make their lives better, but unfortunately this Administration has proven time and time again that the safety and quality of life of the American people doesn’t factor into their decision making. Nevertheless, we will fight hard to reverse this irresponsible decision.”
While mercury and other hazardous air pollutants disproportionately harm people who live near coal- and oil-fired power plants, the emissions can also travel great distances and be deposited into other states. Mercury is a potent neurotoxin that poses serious dangers to public health, especially for pregnant women and children. For example, a pregnant person’s consumption of mercury exposes their child to mercury and can cause lifelong developmental harms and neurological disorders such as seizures, vision and hearing loss, or delayed development. Exposure to mercury also increases the risk of cardiovascular disease, diabetes and autoimmune dysfunction in adults.
Mercury emissions from power plants are also a major contributor to mercury contamination in U.S. waterways. Mercury pollution in lakes and rivers harms the local commercial and recreation fishing economies, as well as tribal nations and indigenous peoples that rely on fishing for subsistence.
The coalition argues that the repeal is unlawful because the EPA has failed to provide a reasoned basis for it and failed to adequately consider developments in practices, processes and control technologies in its attempt to revert to outdated standards. The coalition is asking the court to determine that the rule is unlawful and must be reversed.
Joining Attorney General Neronha in filing this lawsuit are the attorneys general of Arizona, Connecticut, Delaware, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New Mexico, New York, Oregon, Vermont, Washington and Wisconsin, and the District of Columbia, as well as the city of New York, the city of Chicago, and Harris County, Texas.
Date
Tue, 03/31/2026 - 16:42
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