On April 29, the Supreme Court revived EPA’s Cross-State Air Pollution Rule in Environmental Protection Agency v. EME Homer City Generation, L.P., 134 S. Ct. 1584 (2014).  That set of rules would have imposed budgets on air emissions by sources in upwind states in order to implement the “Good Neighbor” provision, section 110(a)(2)(D)(i)(I)  of the Clean Air Act. Justice Ginsburg entirely clear that Congress has provided almost no helpful guidance to EPA and, indeed, the conceptual model of air pollution that underpins the “Good Neighbor” provision is hopelessly simplistic and wrong.

Contrast her opinion with Friday’s decision in National Ass’n of Manufacturers v. Environmental Protection Agency, No. 13-1069 (D.C. Cir. May 9, 2014), denying challenges to recent revisions to the national ambient air quality standard for small particulate matter (“PM2.5″), or today’s decision in WildEarth Guardians v. United States Environmental Protection Agency, No. 13-1212 (D.C. Cir. May 13, 2014), affirming EPA’s rejection of a rulemaking petition seeking to subject coal mines to regulation as stationary sources under the Clean Air Act.  Those opinions makes Clean Air Act rulemaking look straightforward, and the court of appeals’ analyses are right out of an administrative law hornbook.  ButEME Homer City Generation tells a different story in which EPA must make fundamental decisions about the environment, energy policy, and consequently the economy without much statutory help.