Plain-English summary
Court rules EPA cannot use Section 111(d) to regulate sources already covered by Section 112's hazardous air pollutant (
In Westmoreland Mining v. EPA (No. 20-1778), the Supreme Court held that the Environmental Protection Agency may not use Section 111(d) of the Clean Air Act to impose performance standards on existing sources that the Act already regulates under Section 112's hazardous air pollutants (HAP) program. The Court reversed the D.C. Circuit and sent the cases back to the agency.
Why this matters
The decision narrows a major pathway the EPA had used to regulate air pollution from existing sources. It limits the agency’s ability to layer multiple regulatory programs on the same sources, affecting how the EPA designs pollution-control rules and how regulated industries and states plan compliance.
Who may feel it
- Power plants, industrial facilities, and other stationary sources regulated under the Clean Air Act
- State environmental agencies that implement and enforce federal air rules
- Companies in industries that emit hazardous air pollutants
- Communities near regulated facilities concerned about air quality
- The EPA and future rulemaking efforts that target greenhouse gases or other pollutants
Key questions
- May the EPA use 42 U.S.C. § 7411(d) (Section 111(d)) to impose performance standards on existing stationary sources that are already regulated under 42 U.S.C. § 7412 (Section 112) for hazardous air pollutants?