Sierra Club v. Environmental Protection Agency
United States Court of Appeals for the District of Columbia Circuit
551 F.3d 1019 (D.C. Cir. 2008)
Section 112 of the Clean Air Act required EPA (defendant) emission standards to reflect maximum achievable control technology (MACT) resulting in the maximum degree of emissions reduction, and Section 302(k) defined emission standards as limits applying on a continuous basis; the EPA issued MACT standards but exempted sources from them during startup, shutdown, and malfunction (SSM) periods, subjecting sources during those periods only to a general duty to minimize emissions rather than the MACT standards themselves. The Sierra Club (plaintiff) petitioned for review, challenging the SSM exemption as inconsistent with the Act.
Whether the Clean Air Act requires that emission standards promulgated by the Environmental Protection Agency require the maximum degree of reduction in emissions on a continuous basis.