Utility Air Regulatory Group v. EPA

Background

The dispute involves the Environmental Protection Agency and a range of private groups and several States over how the Clean Air Act applies to greenhouse gases from stationary sources like factories and powerplants. The Act’s PSD and Title V programs require permits for “major” sources—defined by numerical thresholds (250 or 100 tons per year) of “any air pollutant.” After Massachusetts v. EPA, EPA issued motor‑vehicle greenhouse‑gas rules and then concluded those rules would make many stationary sources subject to PSD and Title V. To avoid a massive expansion, EPA issued a Tailoring Rule that phased in higher greenhouse‑gas thresholds (including temporary 75,000 and 100,000 ton CO2e levels) and required the “best available control technology” (BACT) for greenhouse gases at certain levels. Multiple parties challenged EPA’s actions in the D.C. Circuit and then this Court.

Reasoning

The Court held that the Act does not allow EPA to treat a source as requiring a PSD or Title V permit solely because of its potential greenhouse‑gas emissions, and EPA may not rewrite the clear statutory 100/250‑ton numerical thresholds to avoid impracticable results. The Court found that applying the statutory thresholds to greenhouse gases would radically and unreasonably expand EPA programs and that an agency cannot “tailor” unambiguous statutory terms. At the same time, the Court concluded EPA permissibly may require BACT for greenhouse gases at sources already covered by PSD because the BACT language applies to “each pollutant subject to regulation,” subject to a sensible de minimis limitation.

Real world impact

As a result, EPA regulations are invalid to the extent they make sources newly subject to PSD or Title V solely on greenhouse‑gas emissions at the statutory 100/250‑ton levels or where EPA rewrote those numbers. EPA may continue to require greenhouse‑gas BACT for sources already requiring PSD permits for conventional pollutants, but must justify any numeric de minimis threshold (the Court did not treat EPA’s 75,000 CO2e number as automatically adequate). The decision narrows EPA’s immediate authority over many small sources and leaves further rulemaking and litigation over specific thresholds and permitting practice.

Dissents or concurrances

Four Justices (Breyer, joined by Ginsburg, Sotomayor, and Kagan) concurred in part and dissented in part, arguing for a different statutory reading that would allow more EPA flexibility on thresholds; Justice Alito (joined by Thomas) partly dissented, warning that BACT is unsuited to greenhouse‑gas regulation.