Clean Air Implementation Project v. EPA

The Environmental Protection Agency (EPA) (defendant) issued standards for emissions by new or modified stationary sources and for emissions of harmful air pollutants. The emissions standards specified the reference test for analyzing air samples to ensure that a standard was being met. The EPA created approximately 130 specified reference tests. The EPA amended its regulations to allow the use of any credible evidence to determine whether a stationary source was meeting the emission standards (the credible-evidence rule). In amending the regulations, the EPA noted that evidence beyond that from the reference tests, including engineering calculations, indirect estimates of emissions, and emissions measurements, could help determine compliance status. Clean Air Implementation Project (the Project) (plaintiff), along with other industry trade associations, challenged the credible-evidence rule soon after it was enacted. The Project argued that the EPA failed to comply with rulemaking procedures and violated the Clean Air Act by requiring states to rewrite their plans for meeting the EPA’s national ambient-air-quality standards. The Project believed that the credible-evidence rule would make the air-quality standards more stringent because air quality would be monitored more frequently. The EPA argued that the credible-evidence rule would not change the emissions standards, and as a result, states would not have to change their emissions plans.