The Ninth Circuit affirmed in part and reversed in part a district court's dismissal of a suit challenging an automobile company's use of diesel-cheat devices to evade compliance with federally mandated emission standards. Two counties argued the company's installation of and modification to the dev...

The Fifth Circuit upheld EPA's decision to reject a challenge to a CAA Title V permit it issued for expansion of a plant in Baytown, Texas. Environmental groups requested that EPA reject the permit on the grounds that the underlying Title I preconstruction permit allowing the expansion was invalid. ...

The First Circuit vacated an air permit issued by the Massachusetts Department of Environmental Protection (MDEP) for a proposed natural gas compressor station that is part of a natural gas pipeline connecting the northeastern U.S. and Canada. Nearby municipalities and citizens argued that MDEP impr...

The D.C. Circuit granted in part and denied in part Delaware's and Maryland's challenges to EPA's denial of their CAA §126(b) petitions requesting that the Agency impose additional limitations on certain upwind sources contributing to the states' nonattainment of ozone NAAQS. Maryland's petition ar...

The D.C. Circuit granted a petition to review EPA's 2017 rule revising its emission standard for hazardous air pollutants (HAPs) emitted from pulp mill combustion sources. Environmental groups argued that EPA was required under §112(d)(6) of the CAA to consider the adequacy of the standard to contr...

The D.C. Circuit affirmed dismissal of an environmental group's request to compel EPA to produce guidelines for commercial or industrial solid waste incinerators (CISWI) and other categories of solid waste incinerators (OSWI). The group argued that the Agency failed to comply with nondiscretionary d...

The D.C. Circuit vacated a 2018 EPA rule that instituted a complete vacatur of its 2015 rule blocking the use of hydrofluorocarbons as replacements for ozone-depleting substances. An environmental group argued the 2018 rule was invalid because it was a legislative rule and was thus improperly promul...