Supreme Court Limits EPA’s Authority to Regulate Carbon Emissions from Stationary Sources

Since the Supreme Court’s 2007 decision in Massachusetts v. EPA, it has been clear that the U.S. Environmental Protection Agency (“EPA”) has the authority under the Clean Air Act (“CAA”) to regulate emissions of greenhouse gases (“GHGs”) from mobile sources because GHGs fall within the CAA’s definition of an “air pollutant.” When EPA sought to regulate GHG emissions from stationary sources (mainly power plants and factories), however, the Court sang a slightly different tune. In Utility Air Regulatory Group v. Environmental Protection Agency (“UARG”), the Court rejected EPA’s attempt to regulate GHG emissions from stationary sources under two regulatory programs based solely on those emissions, while affirming the agency’s ability to regulate such emissions from so-called “anyway” sources that are already undergoing regulatory review because of emissions of other pollutants.