[JURIST] The US Supreme Court [official website] heard oral arguments [day call, PDF] Monday on the federal government’s power to regulate certain greenhouse gases. In United Air Regulatory Group v. EPA [transcript, PDF], which was consolidated with six other cases, the court has limited the grant of review to the following issue: Whether the Environmental Protection Agency (EPA) [official website] permissibly determined that its regulation of greenhouse gas emissions from new motor vehicles triggered permitting requirements under the Clean Air Act [text, PDF] for stationary sources that emit greenhouse gases. Stationary sources are typically electricity-generating utility plants and major factories, and the permitting requirements in question involve the EPA’s authority under the Clean Air Act’s Title I and Title V [texts] to issue permits for construction or modification and operation of stationary sources. In the US Court of Appeals for the District of Columbia Circuit [official website], a three judge panel upheld [opinion, text] the EPA’s determination that greenhouse gases were an endangering pollutant that the EPA was obliged to regulate. The DC Circuit court declined to review the decision en banc, and the Supreme Court granted certiorari [JURIST report] last October.

United Air Regulatory Group v. EPA is not the only controversial case [JURIST op-ed] involving the EPA and the Clean Air Act crossing the Supreme Court’s agenda. In December the court heard oral arguments [JURIST report] in the consolidated cases of Environmental Protection Agency v. EME Homer City Generation and American Lung Association v. EME Homer City Generation [transcript, PDF]. There, the court is considering the authority of the EPA under the Clean Air Act to issue a regulation limiting power plants’ emissions that cross state lines. The questions before the court are (1) whether the court of appeals lacked jurisdiction to consider the challenges on which it granted relief; (2) whether states are excused from adopting state implementation plan (SIPs) prohibiting emissions that “contribute significantly” to air pollution problems in other states until after the EPA has adopted a rule quantifying each state’s interstate pollution obligations; and (3) whether the EPA permissibly interpreted the statutory term “contribute significantly” so as to define 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 unambiguously requires the EPA to consider only each upwind State’s physically proportionate responsibility for each downwind air quality problem. JURIST Guest Columnist John Robinson Jr. examined [JURIST op-ed] the consolidated cases and the EPA’s efforts to address cross-state air pollution.