Environmental Defense v. Duke Energy Corp.

Duke Energy (defendant) modified coal-fired plants to extend their operating life and allow longer daily operation, and Environmental Defense (plaintiff) sued alleging Duke needed a Prevention of Significant Deterioration (PSD) permit for these "modifications," a term also defined for New Source Performance Standards (NSPS) purposes as any change increasing a facility's hourly emissions rate; Duke argued its changes did not increase hourly emissions and so were not "modifications" under either provision, and the lower courts agreed, relying on precedent requiring the same statutory term to be defined identically throughout an act.