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Environmental Defense v. Duke Energy Corp.

ELR Citation: 37 ELR 20076
Nos. No. 05-848, (U.S., 04/02/2007) rev'd

The Court reversed the Fourth Circuit's grant of summary judgment in favor of a coal-fired power plant operator charged with violating the Clean Air Act's (CAA's) prevention of significant deterioration (PSD) regulations. The CAA's PSD and new source performance standards (NSPS) provisions both cover modified, as well as new, stationary sources of air pollution. The Fourth Circuit ruled that the CAA requires the U.S. Environmental Protection Agency to conform its PSD regulations on modification to their NSPS counterparts because the NSPS provisions define the term "modification," whereas the PSD provisions use that word "as defined in" the NSPS. Consequently, it held that the power plant did not violate the CAA when it upgraded its plants in the 1980s and 1990s without a PSD permit. The Supreme Court reversed. Principles of statutory interpretation do not rigidly mandate identical regulation. The presumption that identical words used in different parts of the same statute are intended to have the same meaning and application is not a rigid one. Further, the appellate court's reading of the PSD regulations, intended to align them with NSPS, was inconsistent with their terms and effectively invalidated them. The NSPS regulations require a source to use the best available pollution-limiting technology when a modification would increase the discharge of pollutants measured in kilograms per hour, whereas the PSD regulations require a permit for a modification only when it is a "major" one, and only when it would increase the actual annual emission of a pollutant above the actual average for the two prior years. Souter, J., delivered the opinion of the Court, in which Roberts, C.J., and Stevens, Scalia, Kennedy, Ginsburg, Breyer, and Alito, JJ., joined, and in which Thomas J., joined as to all but Part III–A. Thomas, J., filed an opinion concurring in part.