On April 7, 2020, the U.S. Court of Appeals for the District of Columbia Circuit (DC Circuit) held in Sierra Club v. EPA, No 18-1167, that the Sierra Club’s challenge to EPA’s “Guidance on Significant Impacts Levels for Ozone and Fine Particles in the Prevention of Significant Deterioration Permitting Program” (SILs Guidance) was not reviewable final agency action. The decision represents a significant win for EPA. NSR Law Blog previously discussed the SILs Guidance in May 2018 and June 2018, which see for a copy of the guidance and a discussion of its significance.
