The US Supreme Court issued two rulings on Wednesday that establish where challenges to Environmental Protection Agency (EPA) actions should be filed, remanding one lawsuit to regional circuits and directing the other suit to the US Court of Appeals for the District of Columbia Circuit. In the 6-2 and 7-2 decisions, both authored by Justice Clarence Thomas, the court reinforced a framework for determining venue under the Clean Air Act (CAA).

The lawsuit Oklahoma v. EPA involved a dispute over State Implementation Plans (SIPs), which are state-developed plans that outline how each state will achieve and maintain federal air quality standards, subject to EPA approval. In 2023, the EPA denied the plans submitted by 21 states for violating the CAA’s Good Neighbor Provision, which requires states to prevent emissions that interfere with other states’ ability to meet air quality standards. The EPA bundled all 21 denials into one combined ruling and claimed that challenges belonged in the DC Circuit. Oklahoma, Utah and various fuel industry groups disagreed, filing suit to move their challenges to regional courts.

Wednesday’s ruling determined that the SIP disputes must be heard in regional circuits because the EPA “makes clear that its SIP disapprovals were based on ‘a number of intensely factual determinations’ particular to the State at issue.” The court found that the EPA evaluated each state’s plan “on its own merits” using a unique analysis for each state. The EPA had previously argued that the CAA’s “nationwide scope or effect” exception dictated that because the SIPs had broad, national implications, challenges must be brought in the D.C. Circuit. However, the Supreme Court held that this exception only applies when national implications are the “primary explanation for and driver of” EPA actions, whereas Oklahoma v. EPA involved mostly state-specific facts.

The lawsuit EPA v. Calumet Shreveport Refining addressed a dispute over small refinery exemption petitions, which are annual waivers given to small oil refineries that can demonstrate a “disproportionate economic hardship” from compliance with EPA fuel standards. In 2022, the EPA denied 105 exemption petitions, and refineries filed challenges in various regional circuits. Here, the Supreme Court held that the “nationwide exception” applied because determining disproportionate economic hardship requires comparing refineries across the country. Additionally, the EPA applied these determinations consistently when reviewing individual refineries.

The EPA has been under scrutiny by the Supreme Court in recent months. In April, the court heard oral arguments for an ongoing lawsuit that sees fuel industry groups challenging vehicle emission standards in California. In March, the court barred the EPA from imposing certain types of water quality fines on the city of San Francisco. 

Regional circuits are geographically-based federal courts that handle appeals of lawsuits originating in their local areas, whereas the DC Circuit commonly reviews federal agency actions due to its proximity to government agencies. The concern over venue selection often arises because of perceptions of deferential rulings influenced by geographical and socio-political factors.