On June 12, 2025, Sierra Club, as part of a coalition of environmental and community groups, filed a lawsuit in the United States District Court for the District of Columbia challenging President Trump's decision to exempt 68 coal-fired power plants from compliance with EPA's updated Mercury and AIr Toxics Standards (MATS). Those updated standards, finalized in 2024, require a handful of especially poorly controlled power plants to reduce their emissions of mercury as well as arsenic, chromium, and other air toxics. The President issued a proclamation on April 8, 2025 invoking a never-before-used provision of the Clean Air Act that allows the President to exempt specific sources of pollution from their obligation to comply with air-toxics standards—but only if the technology to implement the standard is unavailable and the exemption serves the United States national security. EPA had earlier invited industries to apply for such exemptions via simple e-mail.
The proclamation applies to coal power plants spread across 23 states: Alabama, Alaska, Arizona, Arkansas, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Montana, New Hampshire, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, West Virginia, and Wyoming. Many of the exempted facilities are located in or near working-class communities and communities of color already burdened by pollution.
The lawsuit contends that the President's exemptions exceeded the authority provided by the Clean Air Act. The technologies required to comply with the MATS update are readily available; indeed, most of the exempted plants need only improve and maintain controls they have already installed. Some of the plants are already meeting the standards for which the President's order claims no compliance technology is available. The order does not—and could not—determine that the required technologies to comply with the standards is available to each of the exempted plants, much less that such technologies will be available two years from now when plants would be required to meet the standards.
Meanwhile, EPA has proposed repealing the MATS update in its entirety. Sierra Club and its allies are preparing comments opposing the repeal.