On May 29, 2025, the Supreme Court issued its Opinion in Seven County Infrastructure Coalition et al. v. Eagle County, Colorado et al., one of the most high-profile National Environmental Policy Act, or NEPA, cases to reach the Supreme Court in decades.

The Seven County Opinion clarifies that NEPA does not require review of a proposed project’s upstream or downstream environmental impacts that may occur in a separate time or place than the project. In doing so, the Opinion includes a full-throated endorsement of the principle of judicial deference to agency decision-making for the scope of NEPA study. The Court further cautions lower courts to avoid the type of “intrusive” judicial review that has contributed to “fewer and more expensive railroads, airports, wind turbines, transmission lines, dams, housing developments, highways, bridges, subways, stadiums, arenas, data centers, and the like.” The decision gives project proponents hope for more certainty in the NEPA process.

The Opinion, however, is not without its challenges, particularly for projects in California. In narrowing the scope of NEPA review, the Court has now potentially widened the gulf between environmental review of projects in California under federal law (NEPA) and State law (the California Environmental Quality Act, or CEQA).

Seven County involves a challenge to the U.S. Surface Transportation Board’s (STB) NEPA review and approval of a proposed 88-mile railroad line in Utah that would connect the oil-rich Uinta Basin to the Country’s national rail network. The D.C. Circuit vacated the approval, finding that the Environmental Impact Statement for the rail line had failed to consider environmental effects resulting from the increased oil drilling upstream in the Uinta Basin and increased oil refining downstream along the Gulf Coast of Louisiana and Texas.

The Supreme Court overturned the D.C. Circuit’s ruling on two grounds. The first concerned how an agency should assess a project’s upstream and downstream impacts. The Court held that NEPA review of a project does not require the review of environmental impacts from other foreseeable projects that are separate in time and place, or other projects which the reviewing agency possesses no regulatory authority over. Requiring otherwise, the Court opined, would break the chain of proximate causation between the proposed project and the environmental effects that are studied. The Court carefully distinguished the concept environmental effects related to foreseeable, but wholly separate projects, from environmental effects resulting from the project under review, even if those effects occur at a later time or extend beyond the geographic footprint of the project. NEPA, for instance, requires that an agency study impacts from a project’s direct runoff that may impact downstream ecosystems, or emissions that may travel downwind to impact separate geographic areas. But it does not require study of runoff or emissions from geographically separate projects that are made possible by approval of the project under review.

Another ground for overturning the D.C. Circuit concerned the scope of judicial review under NEPA. As the Court put it, “the bedrock principle of judicial review in NEPA cases can be stated in a word: Deference.” By focusing on deference in adjudicative proceedings like NEPA review, the Court seeks a “course correction” to align judicial review with NEPA’s text. Specifically, the Court explains that NEPA review requires “a series of fact-dependent, context-specific, and policy-laden choices about the depth and breadth of its inquiry—and also about the length, content, and level of detail of the resulting EIS,” all of which should be afforded substantial deference so long as the choices “fall within a broad range of reasonableness.”¹ In emphasizing that NEPA functions as a purely procedural statute, the Opinion further suggests that a deficient EIS will not necessarily require a Court to invalidate a project approval without further evidence that the agency would have disapproved the project were the EIS corrected.

The Court’s framing of NEPA as a procedural and deferential statute reinforces that NEPA is not designed “for judges to hamstring new infrastructure and construction projects.” This vision stands in stark contrast to the realities of its Californian cousin, CEQA. CEQA, by design, is fundamentally different from NEPA. While CEQA requires that agencies perform environmental review similar to NEPA, it also requires mitigation measures to reduce any significant environmental impacts identified during review. Since the scope of review under CEQA is broader than NEPA, Seven County will likely widen that gulf. For instance, CEQA review of a project requires an analysis and potential mitigation of a range of indirect impacts that may be later in time or removed in distance so long as those impacts are reasonably foreseeable. Seven County makes clear that reasonably foreseeable, but indirect impacts of a project do not necessarily need to be addressed under NEPA.

In other respects, Seven County tracks a wider trend of prioritizing a reduction in delay for certain projects over strict compliance with robust environmental review statutes. California is not immune to this trend—recent California legislation has focused on reducing the CEQA burden borne by housing and infrastructure projects. And recent decisions from California courts have rejected CEQA challenges seeking to expand the ambit of the statute. Whether and how a NEPA review case like Seven County may affect the conversation over how to improve CEQA remains to be seen. But for project proponents, there is optimism.

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¹ The Court briefly discusses the tension between this conclusion and its recent opinion in Loper Bright Enterprises v. Raimondo, explaining that Seven County involves issues of fact rather than issues of statutory interpretation. Determining what NEPA requires for a valid EIS is a legal question subject to de novo judicial review, whether a particular EIS meets those requirements is a factual determination subject to a more deferential standard of review.