U.S. Supreme Court

Case Status


Docket Number



2006 Term


Questions Presented

1. Whether the Fourth Circuit's decision violated Section 307(b) of the Act, which provides that national Clean Air Act regulations are subject to challenge "only" in the D.C. Circuit by petition for review filed within 60 days of their promulgation, and "shall not be subject to judicial review" in enforcement proceedings, 42 U.S.C. 7607(b); and

2. Whether the Act's definition of "modification," which turns on whether there is an "increase" in emissions and which applies to both the NSPS and PSD programs, rendered unlawful EPA's longstanding regulatory test defining PSD "increases" by reference to actual, annual emissions.

Case Updates


April 02, 2007

The Supreme Court ruled against NCLC and upheld the Environmental Protection Agency’s view that changes in power plants that may contribute to air pollution must be made with a permit if there is an annual increase in emissions.

NCLC files amicus brief in case addressing emission restrictions and Clean Air Act

September 15, 2006

In its brief, NCLC argues that Duke Energy’s plan to modernize its electric utility plants does not need to be submitted to the government pursuant to the Clean Air Act’s New Source Review process (NSR) because no major modification of Duke Energy’s permitted operations had occurred. At issue is whether hourly or annual emissions represent the baseline for determining whether NSR governs a particular plant modernization. NCLC argues that if the Supreme Court does not affirm the lower court’s decision, hundreds of commonplace modernization activities would have to undergo NSR analysis even if their hourly emission rates are unchanged and stay below permit levels that already have been approved.

Case Documents