On July 2, 2020, the Tenth Circuit Court of Appeals rendered its decision in Sierra Club v. U.S. EPA, in which Sierra Club sought direct review of the Administrator’s decision in PacifiCorp Hunter Energy, previously discussed in NSR Law Blog. In the Hunter Energy decision, EPA Administrator Pruitt had held that title V objections are not the proper forum for reviewing PSD permitting decisions. EPA appealed, arguing that Title V encompasses “all applicable requirements.” In a decision focusing solely on the regulatory definition, the Tenth Circuit agreed, vacating and remanding the Sierra Club’s petition for objection back to EPA. A circuit split now exists between the Tenth Circuit, which holds that EPA’s regulatory definition and the Utah SIP compel the broadest range of review, and the Fifth Circuit, which holds that the text and structure of the Act make the narrower reading more persuasive. The Fifth Circuit’s decision was previously discussed in NSR Blog.