549 U.S. 561 (2007)
Environmental Defense v. Duke Energy Corporation is a pivotal case in environmental law, specifically interpreting the scope of the Clean Air Act’s New Source Review (NSR) requirements.
Does the definition of 'modification' under the Clean Air Act require considering the total annual emissions potential for determining the necessity of NSR permits for power plants?
Under the Clean Air Act, 'modification' applies to any physical change that causes an increase in emissions, and the determination of emissions increases should consider total annual emissions rather than just hourly rates.
The U.S. Supreme Court held that the term 'modification' should be consistently interpreted with respect to both NSR permits and subsequent enforcement provisions, requiring consideration of total annual emissions rather than solely an increase in hourly emissions rates.
This case is critically significant for law students and practitioners in environmental law, as it clarifies important regulatory requirements under the Clean Air Act. By emphasizing the consistent application of 'modification' within different regulatory contexts, the decision reaffirms the comprehensive approach to managing and controlling air pollution. This case underscores the balance between statutory interpretation and practical regulatory impacts, particularly in determining compliance obligations for industrial facilities.