An affirmative defense provision is provided in some CAA section 111 and 112 regulations (e.g. 40 CFR 63.11895) which allows applicable regulated sources, in a judicial or administrative proceeding, to demonstrate that despite reasonable efforts to avoid a malfunction, an emission standard was violated for circumstances beyond the control of the source. This provision further provides that courts can only assess civil penalties if violators “fail[ed] to meet [their] burden of proving all of the requirements in the affirmative defense.” See 78 Fed. Reg. 10,006, 10,039 (Feb. 12, 2013). In 2014, the D.C. Circuit Court vacated the affirmative defense provision in one of the EPA’s CAA section 112 regulations. NRDC v. EPA, 749 F.3d 1055 (D.C. Cir. 2014). The court held that the EPA exceeded its statutory authority when establishing the affirmative defense and held that the authority to determine civil penalty amounts lies exclusively with the courts. Consequently, the EPA has been removing the affirmative defense provision from individual rules as each rule is opened for periodic review. This action will further progress more efficiently by removing the affirmative defense provision from numerous CAA section 111 and 112 rules in a single action.