Decision in EME Homer City upholds CSAPR, but additional legal challenges and EPA revisions may still significantly alter CSAPR and delay its implementation.

On Tuesday, April 29, the United States Supreme Court upheld EPA’s Cross-State Air Pollution Rule (CSAPR) in a 6-2 decision. The Court’s ruling in EPA v. EME Homer City Generation follows a long and highly contentious regulatory process that included: EPA’s development of a prior rule regulating interstate transport of air pollution, the Clean Air Interstate Rule (CAIR) in 2005; the U.S. Court of Appeals for the D.C. Circuit’s (D.C. Circuit) rejection of CAIR in 2008; EPA’s development of CSAPR as a replacement rule in 2011; and the D.C. Circuit’s decision to vacate CSAPR in August 2012. The Supreme Court’s decision on Tuesday overturns the D.C. Circuit’s 2012 ruling and reinstates CSAPR. EPA has announced that CAIR will continue to remain in place pending EPA’s review of the Court’s recent holding.

Overview of the Decision -

The majority opinion in EME Homer City, authored by Justice Ruth Bader Ginsberg, includes two key holdings: (1) EPA was not required to provide the States another opportunity to develop state implementation plans (SIPs) allocating in-state emissions of air pollutants after EPA set emissions budgets for the States in CSAPR and could proceed to issue a federal implementation plan (FIP) without States’ input; and (2) EPA’s decision to allocate emission reductions in upwind States on the basis of control costs rather than proportional contributions of pollution to downwind States was a reasonable interpretation of the Clean Air Act’s Good Neighbor Provision and EPA’s decision is therefore entitled to Chevron deference.