Removal of Affirmative Defense Provisions from Specified New Source Performance Standards and National Emission Standards for Hazardous Air Pollutants

Rule Summary

“Affirmative defense” provisions were included by the EPA in a number of 40 CFR parts 60 and 63 rules between the years 2010 to 2014. An “affirmative defense”, in the context of the regulations addressed here, means that, in a judicial or administrative proceeding, if a source could demonstrate that it had met the requirements of the affirmative defense provided in the regulation, civil penalties would not be assessed. This provision would most likely be applied to malfunction events that violate compliance with an emission standard. Malfunctions, as defined in the regulations addressed here, are a sudden, infrequent, and not reasonably preventable failure of air pollution control and monitoring equipment, process equipment, or a process to operate in a normal or usual manner.

In 2014, the D.C. Circuit court vacated the affirmative defense provision in one of the EPA’s Clean Air Act (CAA) section 112 rules, the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Portland Cement Manufacturing. NRDC v. EPA, 749 F.3d 1055 (D.C. Cir., 2014). The court found that the EPA lacked authority to establish an affirmative defense for private civil suits and held that under the CAA, the authority to determine civil penalty amounts in such cases lies exclusively with the courts, not the EPA. Since the decision, the EPA has been removing affirmative defense provisions from CAA section 111, 112 and 129 rules as they were revised or amended. The 2024 proposal addressed removing the affirmative defense provision from a number of rules in a single notice. The 2025 final rule removes affirmative defense from one rule, the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Polyether Polyols Production (PEPO).