Cross-State Air Pollution Rule Vacated By The D.C. Circuit

On August 21, 2012, the D.C. Circuit issued a 2-1 opinion in EME Homer City v. EPA vacating the Cross-State Air Pollution Rule (CSAPR). CSAPR, adopted in 2011, represented EPA's latest effort to address the "good neighbor" provisions of the Clean Air Act, which prohibit emissions from one state from causing or contributing to violations of the national ambient air quality standards in downwind states. Extending on its predecessor, the Clean Air Interstate Rule (CAIR), CSAPR would have established a cap-and-trade program requiring significant reductions in emissions of sulfur dioxide, oxides of nitrogen, and particulate matter from power plants across the eastern two-thirds of the U.S. The court concluded that CSAPR exceeded EPA's statutory authority for two general reasons summarized below, and vacated those rules. However, the Court reaffirmed the decision it made following its finding of legal error in the CAIR rules (in the North Carolina v. EPA case¹) to continue