The U.S. Environmental Protection Agency (EPA) has finalized rulemaking originally proposed in 2016 to remove "emergency" affirmative defense provisions from its Clean Air Act (CAA) permitting regulations for "major sources." On July 21, the EPA published a final rule amending 40 C.F.R. Sections 70.6 and 71.6 to delete the emergency affirmative defense provisions in light of decisions from the U.S. Court of Appeals for the D.C. Circuit.