Mechanical things occasionally break and sometimes do not work as designed despite best a company's best efforts. This seemingly unavoidable reality has been at the heart of a decade old dispute between EPA, States and industry. On March 1, 2024, the U.S. Court of Appeals for the District of Columbia Circuit largely resolved the dispute, at least for now, by vacated EPA's “SIP Call” that required states to remove from their respective air quality plans regulatory waivers for excess air emissions during periods of emission unit startup, shutdown, and malfunction (SSM). The court held that EPA did not make the necessary or appropriate determination required by the Clean Air Act to order states to eliminate automatic SSM exemptions, director's discretion provisions, and affirmative defenses that function as SSM exemptions. The decision is a victory for industry and those states that have SSM automatic exemptions, director’s discretion and general affirmative defense regulations.