The Sixth Circuit vacated EPA's determination that a natural gas operation's plant and production wells separately located within a 43-square-mile area constitute a single stationary source under the CAA Title V permitting program. EPA concluded that the facilities satisfy the regulatory requirement...

The Fifth Circuit upheld an EPA rule partially approving and partially disapproving revisions to Texas' SIP concerning civil penalties for excess emissions resulting from startup, shutdown, and malfunction (SSM) activities. Environmental petitioners sought review of EPA's decision to approve a revis...

The D.C. Circuit denied petitions challenging EPA's one-hour primary NAAQS for nitrogen dioxide (NOx). The new one-hour primary NAAQS requires that “the three-year average of the annual 98th percentile of the daily maximum one-hour average concentration be less than or equal to 100 parts per billi...

The D.C. Circuit dismissed petitions challenging EPA's primary NAAQS for sulfur dioxide (SO2). The petitioners—several states, state regulatory agencies, corporations, and industrial associations—argued that EPA failed to follow the APA's notice-and-comment rulemaking procedures because it did n...

The D.C. Circuit upheld four EPA rulemakings governing greenhouse gases. EPA issued the rules following the U.S. Supreme Court's decision in Massachusetts v. EPA, 549 U.S. 497 (2007), in which the Court clarified that greenhouse gases meet the definition of an air pollutant under the CAA. Petit...