On December 10, 2013 the Supreme Court heard oral arguments in EPA v. EME Homer City Generation. The case presents three questions: (1) Whether the court of appeals had jurisdiction to consider the challenges to the Clean Air Act on which it granted relief; (2) whether states may wait until after the EPA has adopted a rule which specifies each state’s inter-state pollution obligations to adopt state implementation plans that ban emissions that “contribute significantly” to other states’ air pollution problems; and (3) whether the EPA correctly interpreted the Clean Air Act’s phrase “contribute significantly” by defining each upwind state’s “significant” interstate air pollution contributions in light of the cost-effective emission reductions it can make to improve air quality in polluted downwind areas, or whether the Act instead requires the EPA to simply consider only each upwind state’s physically proportionate responsibility for each downwind air quality problem. -- To discuss the case, we have Mark DeLaquil who is a partner at Baker Hostetler.