“Duking” It Out – Supreme Court Decides Major Clean Air Act Case Regarding Modification of Facilities

On April 2, 2007, the U.S. Supreme Court addressed what constitutes a “modification” at a facility that will

trigger new source review (NSR) under the Clean Air Act (CAA). Environmental Defense v. Duke Energy Corp.,

No.05-848. The decision is “Round One” on the modification question, with the case remanded to the lower court for additional proceedings. A final decision will affect all industrial plants subject to NSR and air permitting

under prevention of significant deterioration (PSD) regulations.