In a case that could open the door to more citizen suits to enforce mobile source provisions of the Clean Air Act—a category of enforcement actions that has so far failed to gain much traction—the 10th Circuit Court of Appeals recently issued an opinion broadly upholding a non-profit organization’s standing. Utah Physicians for a Healthy Environment v. Diesel Power Gear, LLC  involved claims that the defendants had violated Title II of the Clean Air Act in a number of ways, including by removing emission-control devices from diesel trucks, selling and installing after-market defeat devices, and operating vehicles without proper emission-controls devices. The plaintiff, the non-profit Utah Physicians for a Healthy Environment (“UPHE”), claimed the emission of pollutants associated with the violations “contribute[d] to the adverse [health] effects” of its members, and forced them to avoid certain outdoor recreational activities. At the trial court, UPHE was awarded partial summary judgment, and other claims were adjudicated in its favor during a bench trial. The trial court found that statutory penalties of up to $117,290,620 were allowed, but awarded no more than $333,700 against any single defendant. The trial court also issued an injunction prohibiting the defendants from engaging in any of the activities prohibited by the Act. 

The primary issue on appeal was the UPHE’s standing to bring the claims, and particularly whether its members established causation between their injuries and the defendants’ conduct. The defendants argued that, under the Clean Air Act, UPHE was required to show that the wrongful emissions made a “meaningful contribution” to its members’ injuries. And because any pollution that resulted from the defendants’ violations was only a “negligible fraction of the total pollution that comes from a myriad of sources” in the area, there was no legal causation. 

The 10th Circuit disagreed. First, the court rejected the “meaningful contribution” causation standard. Instead, it found that UPHE had to show only that its members’ injuries were “fairly-traceable” to the defendants’ violations. The “meaningful contribution” language was used by the U.S. Supreme Court in holding, in the landmark decision Massachusetts v. E.P.A., that EPA could regulate greenhouse gas emissions under the Clean Air Act. According to the UPHE court, however, the relevance of the meaningful contribution requirement (in that case, of U.S. auto sector carbon emissions) was to address the less-direct causal chain between atmospheric greenhouse gases and sea level rise in Massachusetts. It did not apply to UPHE’s claims that tailpipe emissions harmed its members’ health.  

Furthermore, the court stressed the importance of citizen suits to holding relatively small polluters accountable under the country’s environmental laws. The primary purpose of citizen suit provisions is to expand the potential claimants—and thus enforcement resources—so that cases might be brought against violators that the government would not otherwise have the resources to hold accountable. To limit standing to cases involving only the largest sources of emissions would effectively bar citizen suits in most of the relatively small cases where Congress intended them to play the largest role. 

The court did reverse the lower court and find that UPHE lacked standing with respect to one portion of its claim: violations that depended on vehicles that were never driven in the airshed where UPHE members live. Any such violations would only have resulted in emission that were too geographically remote to sufficiently affect UPHE’s members. This line drawing, although meaningful, only reinforces just how minimal the environmental impact of a violation must be in order to constitute the legal cause of harm for standing purposes. The result, as the court found, is that “[i]f the vehicle was driven, however little, in the Salt Lake City area, UPHE has established that its members’ injuries from excessive pollution can be fairly traced to the CAA violation.” 

The UPHE decision seems to invite Clean Air Act mobile source citizen suits, particularly by environmental organizations. Although climate change cases may be an exception, the reasoning of the case suggest that a group has standing to bring a claim for nearly any violation that the results in some increased emissions in an area of the country where the organization has at least one member. That likely covers most of the country, if the right plaintiff organization is interested in pursuing the claim.

As a result, relatively small-scale mobile source standard violators that have been getting by largely under the agency enforcement radar could see a bumpier road ahead.