Today, the U.S. Court of Appeals for the D.C. Circuit vacated the Cross-State Air Pollution Rule (CSAPR) in EME Homer City Generation L.P. v. EPA. The court held that CSAPR exceeded EPA’s authority under the Clean Air Act because the rule would require upwind states to reduce emissions beyond their significant contribution to downwind state nonattainment with the NAAQS. Under the good neighbor provision in § 110(a)(2)(D)(i)(I) of the Clean Air Act, EPA has the authority to require upwind states the reduce only their significant contribution to a downwind state’s nonattainment, and the court held that requiring additional reductions violates the Clean Air Act. In addition, the D.C. Circuit vacated the 59 Federal Implementation Plans (FIPs) that EPA issued simultaneously with CSAPR, holding that EPA improperly departed from its consistent prior approach by denying states the initial opportunity to implement the required reductions from sources within their borders. Under the Clean Air Act, states are required to submit State Implementation Plans (SIPs) that meet the requirements of the good neighbor provision within three years after the promulgation or revision of a primary NAAQS. EPA is only allowed to promulgate a FIP after it has determined that a state has failed to make a required SIP submission or after EPA has disapproved a SIP.

The court’s decision was split 2-1, with Judges Kavanaugh and Griffith in the majority and Judge Rogers in dissent. In her dissent, Judge Rogers wrote that the court had exceeded its jurisdiction and “trampl[ed]” on the court’s prior precedent. The court required EPA to continue administrating the Clean Air Interstate Rule (CAIR) pending the promulgation of a valid replacement. The D.C. Circuit previously remanded CAIR to EPA without vacating the rule in North Carolina v. EPA. The panel also instructed the Clerk withhold issuance of the mandate seven days after disposition of any timely petition for rehearing or petition for rehearing en banc.