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Massachusetts v. Environmental Protection Agency

ELR Citation: 37 ELR 20075
Nos. 05-1120, (U.S., 04/02/2007)

The Court held that the U.S. Environmental Protection Agency (EPA) has the statutory authority to regulate greenhouse gases (GHGs) from new motor vehicles. The case arose after private organizations petitioned EPA to begin regulating four GHGs, including carbon dioxid (CO2), under the Clean Air Act. EPA rejected the petition, and the petitioners, joined by Massachusetts and other state and local governments, sought review in the D.C. Circuit, which upheld EPA's determination. The Supreme Court reversed. First, the Court rejected EPA's argument that a causal link between GHGs and the increase in global surface air temperatures was not unequivocally established. The harms associated with climate change are serious and well recognized, and given EPA's failure to dispute the existence of a causal connection between man-made greenhouse gas emissions and global warming, its refusal to regulate such emissions, at a minimum, contributes to petitioners' injuries. Further, while regulating motor-vehicle emissions may not by itself reverse global warming, it does not follow that the Court lacks jurisdiction to decide whether EPA has a duty to take steps to slow or reduce it. Hence, the petitioners have standing. As for the merits, the Court held that because GHGs fit well within the Act's capacious definition of "air pollutant," EPA has statutory authority to regulate the emission of such gases from new motor vehicles. That definition embraces all airborne compounds of whatever stripe. Also unpersuasive was EPA's argument that its regulation of motor vehicle CO2 emissions would require it to tighten mileage standards, a job (according to EPA) that Congress has assigned to the U.S. Department of Transportation. The Court also ruled that EPA rejected the petition on impermissible grounds. Instead of determining that GHGs do not contribute to climate change or providing some reasonable explanation as to why it cannot or will not exercise its discretion to determine whether they do, EPA offered a laundry list of reasons not to regulate. EPA's policy judgments have nothing to do with whether GHGs emissions contribute to climate change and do not amount to a reasoned justification for declining to form a scientific judgment. On remand, EPA must ground its reasons for action or inaction in the statute. Stevens, J., delivered the opinion of the Court, in which Kennedy, Souter, Ginsburg, and Breyer, JJ., joined. Roberts, C.J., filed a dissenting opinion, in which Scalia, Thomas, and Alito, JJ., joined. Scalia, J., filed a dissenting opinion, in which Roberts, C.J., and Thomas and Alito, JJ., joined.