EPA v. Calumet Shreveport Refining, LLC

The Clean Air Act's hardship exemption turns on whether a refinery demonstrates "disproportionate economic hardship," but the statute's text left ambiguous whether EPA could grant exemptions to refineries whose prior exemptions had lapsed or only to those maintaining continuous exempted status. The petitioners' competing claims—some asserting continuous exemption entitlements and others seeking reinstatement after a lapse—directly implicated this interpretive gap, making EPA's authority to grant current relief depend entirely on how broadly or narrowly the statute's exemption language was read. The Court's determination resolved whether the statute permits EPA to evaluate hardship based on present-day circumstances alone, independent of a refinery's exemption history, or whether the statutory language incorporates a continuity requirement that forecloses reinstatement.