The Third Circuit has rejected an environmental group’s citizen suit against a Pennsylvania coke plant, finding that regulators' “diligent prosecution” of the plant bars their claims for Clean Air Act violations. The ruling in the case Group Against Smog and Pollution (GASP) v. Shenango, Inc., No. 15-2041 (3rd. Cir. Jan. 6, 2016) (GASP), could restrict environmental groups' ability to pursue Clean Air Act citizens’ suits in the 3rd Circuit and elsewhere. 

GASP sued Shenango in 2014 for alleged violations of applicable opacity limits, even though a prior U.S. District Court enforcement action (brought by EPA, the Pennsylvania Department of Environmental Protection, and the Allegheny County Health Department (ACHD), which enforces the Pennsylvania State Implementation Plan (SIP)), had previously concluded through a Consent Decree addressing opacity violations. The court retained jurisdiction for the purposes of enforcing the consent decree. Subsequent legal action by ACHD against Shenango in Pennsylvania state court in 2014 resulted in a further Consent Order and Agreement, which reaffirmed the 2012 Consent Decree and addressed further claims of emissions violations. 

The district court dismissed GASP's claims, on the basis that the air regulators’ “diligent prosecution” of their enforcement action against Shenango, which addresses the same alleged violations deprived the court of its jurisdiction to hear the case. The Clean Air Act’s citizen suit provisions state that no citizen action may be commenced “if the [EPA] Administrator or State has commenced and is diligently prosecuting a civil action in a court of the United States or a State to require compliance with the standard, limitation, or order.” 

On appeal, the Third Circuit also found that the “diligent prosecution” bar applied to GASP’s claims, but not due to a lack of jurisdiction. Instead, the 3rd Circuit found that the regulators’ enforcement action barred the GASP citizen suit, regardless of whether or not that enforcement action had ended. The Court stated, “We hold that when a state or federal agency diligently prosecutes an underlying action in court, the diligent prosecution bar will prohibit citizen suits during the actual litigation as well as after the litigation has been terminated by a final judgment, consent decree, or consent order and agreement.” 

In reaching its decision, the 3rd Circuit cited rulings by the 1st, 4th, 7th and 10th Circuits to support its position. The court's holding is expected to limit the ability of environmental groups to bring suit under the Clean Air Act's citizen suit provisions in cases where regulatory agencies have already brought enforcement actions.