Massachusetts v. Environmental Protection Agency
Massachusetts, with eleven other states and three cities, sued the Environmental Protection Agency (EPA) for an injunction requiring the agency to regulate carbon dioxide emissions from new motor vehicles using its authority under § 202(a)(1) of the Clean Air Act, found in 42 U.S.C. § 7521(a)(1). Massachusetts had petitioned the EPA to regulate greenhouse gases because of concerns over global warming, but the EPA claimed it did not have the statutory authority to regulate greenhouse gases and would not do so even if it did.
The United States Court of Appeals for the District of Columbia Circuit denied the injunction, but issued no majority opinion. The two circuit judges who voted to deny the injunction did so for very different reasons. One judge thought that the complaints should be dismissed because global warming does not injure the plaintiffs in a personal way and so they do not have standing under Article III of the Constitution to bring the case. The second judge decided that the EPA reasonably denied the plaintiffs' petition because the studies on the effects of greenhouse gases were not conclusive and the Administrator has broad leeway in making policy judgments.
Questions Presented:
(1) Whether the EPA Administrator may decline to issue emission standards for motor vehicles based on policy considerations not enumerated in section 202(a)(1).
(2) Whether the EPA Administrator has authority to regulate carbon dioxide and other air pollutants associated with climate change under section 202(a)(1).




