On November 16, 2017, the D.C. Circuit heard oral argument in the cases challenging EPA’s 2012 rule allowing states to rely on compliance with the Cross-State Air Pollution Rule (CSAPR) to satisfy electric generating units’ “best available retrofit technology” (BART) requirements for emissions of nitrogen oxides and sulfur dioxide under the Clean Air Act (CAA). The cases are UARG v. EPA, No. 12-1342 and consolidated cases (D.C. Cir.).