EPA Proposes Removing Affirmative Defense Provisions from Eighteen Clean Air Act Emission Standards

In a proposed rule published on June 24, 2024, EPA has proposed to remove eighteen affirmative defense provisions for malfunctions associated with violations of New Source Performance Standards (NSPS) and National Emission Standards for Hazardous Air Pollutants (NESHAP) under the Clean Air Act (CAA). 

These provisions provide an affirmative defense to civil penalties when the event that causes an exceedance of the emission limit is due to 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.” See 40 CFR 63.2 and 40 CFR 60.2. Comments on this proposed rule were due to EPA by August 8, 2024.

EPA proposes to remove the affirmative defense definition, as well as revise or remove and reserve regulatory sections that contain affirmative defense provisions from the eighteen source sector rules shown below:

An affirmative defense as defined in each of the subparts in the table above, means “. . . in the context of an enforcement proceeding, a response or defense put forward by a defendant, regarding which the defendant has the burden of proof, and the merits of which are independently and objectively evaluated in a judicial or administrative proceeding.” As previously stated, the definition of a malfunction in relation to these standards is “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.” The affirmative defense provisions provided that a source would not be subject to civil penalties if it could sufficiently demonstrate in a judicial or administrative proceeding that the violation of emission standards was due to malfunctions as defined by the regulations.

EPA has case-by-case enforcement discretion that provides some flexibility, but after a 2008 United States Court of Appeals for the District of Columbia Circuit case, EPA sought to provide a more formalized approach to malfunction related enforcement via affirmative defense provisions. Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008). The Court in that matter vacated portions of two provisions governing the emissions of hazardous air pollutants during periods of startup, shutdown, and malfunction in EPA's CAA section 112 General Provisions regulations. Subsequently in 2014, the court in NRDC v. EPA, 749 F.3d 1055 (2014), held that EPA lacked authority to establish an affirmative defense for private civil suits and held that CAA section 304(a) clearly vests the authority over private suits exclusively with the courts, not EPA. Additionally, this court vacated the portion of EPA's CAA section 112 regulation pertaining to the affirmative defense in the NESHAP for the Portland cement manufacturing industry.

EPA has been removing affirmative defense provisions from CAA section 112 and section 111 rules since NRDC. Although NRDC pertains only CAA section 112, EPA stated the court's rationale applies to affirmative defense provisions in CAA section 111 rules as well. EPA has removed affirmative defense provisions from those rules when they were otherwise revised or amended.

In November 2014, EPA granted an administrative petition regarding the removal of affirmative defense provisions in twenty-nine regulations. EPA stated it would continue the process of removing affirmative defenses from the remaining rules included in the petition as expeditiously as practicable. EPA also noted the practice of removing the affirmative defense provision from individual rules as the rules are opened for periodic review.

EPA highlighted a few ways a source may have a path for recourse once the affirmative defense provisions are removed. EPA made clear that it will continue to evaluate violations on a case-by-case basis and use discretion when determining whether an enforcement action is appropriate. Moreover, EPA pointed out a source can raise any and all defenses in response to enforcement actions brought under CAA section 113(d)(2)(B) for a violation of an emission standard, and the federal district court will determine what, if any, relief is appropriate. Additionally, EPA emphasized that the presiding officer in an administrative proceeding can consider any defense raised and determine whether administrative penalties are appropriate. Lastly, EPA reiterated the NRDC court’s holding that in a citizen enforcement action brought under CAA section 304(a), the reviewing court has the discretion to consider any defense raised when determining whether penalties are appropriate.

Owners and operators of facilities regulated by the aforementioned eighteen emission standards should weigh whether the potential removal of the affirmative defense provisions warrants revamping current operations, maintenance, and training procedures to proactively decrease the chance of malfunctions that could cause costly emission standard violations. As previously mentioned, comments on this proposed rule must have been received by EPA by August 8, 2024.

89 Fed. Reg. 52425 (June 24, 2024)