EPA Region 6 has proposed to withdraw a 2015 finding that Texas’s State Implementation Plan (SIP) is substantially inadequate to comply with the Clean Air Act (CAA) because of state rules that provide an affirmative defense for excess air emissions that occur during upsets and unplanned maintenance, startup, and shutdown activities. 82 Fed. Reg. 17,986 (Apr. 29. 2019). Region 6 is now proposing to find that Texas’s affirmative defense provisions for so-called “startup, shutdown, and malfunction” or “SSM” events are “narrowly tailored and limited to ensure protection of the National Ambient Air Quality Standards (NAAQS),” as required by EPA guidance. Accordingly, Region 6 is proposing to withdraw EPA’s 2015 “SSM” SIP call issued to Texas based on the finding of substantial inadequacy.

While EPA’s proposed action only affects Texas, the proposal states that the Region 6 Regional Administrator is “considering reinstating EPA’s policy that affirmative defense provisions in the SIPs are generally approvable in the states in Region 6.” Nonetheless, EPA took pains in the proposal to limit its proposed action to Region 6, so the Agency’s action is not particularly helpful to states outside of Region 6 who were also subject to the Agency’s 2015 SSM SIP call. Interestingly, EPA Region 6 characterized its proposed action as a departure from national policy based on the specific circumstances applicable to Texas and sought concurrence from EPA headquarters under a CAA regulation that allows a region to vary from national policy after receiving such a concurrence.


In 1999, EPA policy allowed SIPs to contain affirmative defenses to civil penalties as long as they were narrowly tailored and limited to ensure protection of the NAAQS and other CAA requirements. In 2010, under the Obama Administration, EPA approved the Texas affirmative defense provisions as consistent with that guidance. EPA’s approval of the affirmative defense provisions was challenged by environmental groups as inconsistent with the CAA, but in 2013, the 5th Circuit Court of Appeals upheld EPA’s approval of the Texas rules as consistent with the Act in Luminant Generation Company v. EPA. 714 F.3d 841 (Fifth Cir. 2013, cert. denied).

Shortly before the Fifth Circuit’s decision in Luminant, EPA proposed its SSM SIP Call to find that numerous state SSM rules, including the Texas affirmative defense provisions, were inconsistent with the CAA. In 2015, EPA finalized the SSM SIP call prohibiting all SSM affirmative defenses, even though the Texas affirmative defense provisions had already been upheld by the Fifth Circuit.

Texas submitted a revised affirmative defense rule to EPA in response to the SIP call in November 2016. In March 2017, Texas sought reconsideration of the SIP call as applied to Texas and EPA’s April 29th proposal is the result of that reconsideration.

EPA’s April 29th Proposal

EPA’s proposal, which it characterizes as an “alternative interpretation” to the 2015 SIP call, states that EPA Region 6 believes “it is not appropriate” to extend a 2014 holding of the D.C. Circuit in NRDC v. EPA to state SIPs (and “particularly inappropriate” in the case of Texas, whose affirmative defense provision had already been upheld by the Fifth Circuit). In that case, the court held that EPA had failed to show that affirmative defenses for malfunctions comply with Section 112 of the Clean Air Act, but expressly reserved the question of whether such defenses may be adopted into state implementation plans under Section 110. Accordingly, EPA Region 6 proposed to find that it has discretion to interpret the CAA in a manner consistent with the 5th Circuit’s decision in Luminant and to “permit certain affirmative defense provisions in the section 110 SIPs of states in Region 6.”

However, the holding in Luminant does not actually govern many of the Region 6 states. Furthermore, while the 5th Circuit holding in Luminant extends to Mississippi, it is not in Region 6, so Mississippi would need a separate action by Region 4 before applying Region 6’s proposed “alternative interpretation.” Nevertheless, EPA’s proposal to withdraw the SSM SIP call for Texas articulates a position that states have greater authority to adopt affirmative defense provisions under Section 110 of the CAA than EPA has under Section 112. If this action is finalized as proposed, it will undoubtedly be challenged. This will give the 5th Circuit the opportunity to revisit its 2013 decision in Luminant upholding Texas’s affirmative defense provisions against the backdrop of more recent D.C. Circuit decisions, including NRDC, which limit EPA’ authority to establish affirmative defenses under Section 112 of the Act.