On June 18, 2025, the Supreme Court decided EPA v Calumet Shreveport Refining, LLC et al., and its companion case Oklahoma et al. v. EPA, clarifying the tripartite framework for determining venue in Clean Air Act (“CAA” or “Act”) litigation.  Looking at the CAA's venue provision (42 U.S.C. 7607(b)(1)), the Court explained that if a challenge is to an “nationally applicable” EPA action the challenge should be directed to the U.S. Circuit Court of Appeals for the D.C. Circuit and the matter ends there.  But, if the challenge is to a “locally or regionally applicable” EPA action, then typically those challenges belong in the relevant regional Circuit Court.  However, when a “locally or regionally applicable” action falls within the “nationwide scope or effect” exception, which requires the action be (1) “based on a determination of nationwide scope or effect” and (2) accompanied by an EPA finding to the same effect, the Court instructed that the matter should be routed back to the D.C. Circuit.  Applying this understanding of CAA's venue provision, the Court reached different conclusions in Calumet and Oklahoma, finding respectively that the “nationwide scope or effect” exception applied in one instance and not in the other.

The threshold inquiry, the Court announced, was ascertaining the relevant EPA “action,” because the Act “pegs venue to the scope of the EPA action being challenged.”  It continued that the “action” must be determined by reference to the particular CAA provision authorizing EPA's action, rather than the particular packaging the Agency uses.  For example, in Calumet, the EPA denied over 100 petitions from small refineries essentially seeking exemptions from compliance with the CAA's renewable fuel program (“RFP”) based on their alleged “disproportionate economic hardship.”  In denying these petitions, the EPA chose to issue two omnibus notices: one denying 36 petitions in a single notice, and another denying 69 petitions in a second notice.  Instead of treating the omnibus notices, as EPA’s “action” (i.e., the packaging), the Court emphasized that the Agency’s “action” was the denial of a single refinery exemption petition, and, in turn, looked to the Act’s text authorizing EPA’s denials.  Looking at the face of the authorizing statutory provision, the Court explained that EPA's denial of a single refinery petition only applies to that one refinery, “which is a particular entity located in a particular place.”  Thus, the action was “locally or regionally applicable.”

Because the underlying action in Calumet was deemed to be “locally or regionally applicable,” the Court then moved to determine whether the “nationwide scope or effect" exception applied.  After quickly deciding that the Agency’s action was accompanied by the requisite EPA finding, the Court turned its attention to whether the regionally or locally applicable action was “based on a determination of nationwide scope or effect.” 

Initially, the Court explained that a “determination” is a justification for the action.  Next, it explained that a “determination” is of “nationwide scope or effect,” when the justification applies legally throughout the country or in effect throughout the county.  The Court, however, recognized that all EPA actions have some nationwide justification, so the nexus between the action and determination required by the phrase “based on” was crucial to the analysis.  On this point, the Court, concluded that a determination of nationwide scope or effect must be the “primary explanation for and driver of EPA's action.” Importantly, the Court added that courts should evaluate whether EPA's action is based on a determination of nationwide scope or effect de novo, making Court’s the ultimate arbiter of where venue should be in CAA litigation.

With this framework in mind, the Calumet Court concluded that the “nationwide scope or effect” exception applied and, therefore, venue was proper in the D.C. Circuit.  The Court found that EPA's justifications of (1) a particular Agency-wide statutory interpretation of "disproportionate economic hardship" and (2) pass-through theory that normally small refineries do not suffer disproportionate economic hardships from RFP compliance because they can pass it along to their consumers, were justifications of nationwide scope or effect.  In the words of the Court “[b]oth points apply generically to all refineries, regardless of their geographic location.”  The Court then deemed EPA's action “based on” (i.e., the primary justifications) these justifications because they created a presumption that each petition should be denied, and only considered site specific facts to see if the presumption should be overcome.

The companion case, Oklahoma v. EPA, provides a counterexample on the “nationwide scope or effect” exception.  In Oklahoma, the Court considered proper venue for EPA's disapprovals of two state emission control plans, otherwise known as state implementation plans ("SIPs").  In similar fashion to the EPA's packaging in Calumet, the Agency issued its disapprovals for certain SIPs in one omnibus rule, but the Court determined that the “action” for venue purposes was EPA's individual denials of Oklahoma and Utah's SIPs.  In short order, the Court determined that such disapprovals were “locally or regionally applicable,” this time looking to the fact that the Act specifically enumerated the approval of a SIP as a “locally or regionally applicable” action.  The Court, however, changed course from Calumet on the applicability of the “nationwide scope or effect” exception.  Siding against EPA in this instance, the Court determined that the EPA's disapprovals were not “based on determinations of nationwide scope or effect” because the EPA’s decisions were heavily based on fact specific determinations particular to the relevant States.  Delineating the scope of the exception, the Court highlighted that whereas in Calumet the nationwide factor “all but settled” EPA's action, in Oklahoma EPA's disapprovals of SIPs were primarily motivated by “factual-intensive, state specific analysis.”

Overall, the Court's decisions certainly provide litigants and courts with a framework for determining venue in CAA litigation.  Indeed, following the decisions’ framework step by step should not prove difficult for litigants and courts.  The hope is that this will limit CAA venue litigation reducing the significant time and resources spent just deciding where parties should be arguing.  However, the framework certainly is not beyond some malleability.  In fact, the dissent raises this particular concern questioning whether the framework as expounded by the majority will inject confusion in CAA venue litigation.  One example is the apparent malleability of deciding whether the “nationwide scope or effect” is the primary justification or a lesser one for the Agency's action.  To be sure, in Oklahoma, the EPA relied on the same nationally applicable 4-part framework in evaluating SIPs, but the Court decided this was not sufficiently a “primary” justification of the EPA’s actions.  The dissent noted that while this may be the correct answer, reasonable minds could certainly differ on this point.  Therefore, this line between “primary justifications” and lesser ones may be one area we will see CAA venue litigation moving forward, but time will only tell if the dissent’s concerns are more theoretical than practical.  

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