Key Contacts
Key Supreme Court Environmental Law Rulings: 2025 Highlights and 2026 Outlook
The United States Supreme Court issued several impactful decisions in environmental law cases in 2025 and is set to hear or consider several more in 2026.
Cases Decided in 2025
City and County of San Francisco, California v. EPA, 145 S. Ct. 704 (2025)
In March, the Court held, in a 5-4 decision, that the Clean Water Act does not authorize the EPA to include so-called “end-result” provisions in NPDES permits, which are provisions that hold the permittee responsible for water quality in the body of water into which the permittee discharges pollutants. Under these provisions, a permittee could be penalized if that body of water does not meet certain standards, even if the permittee has followed all specific discharge requirements set forth in its permit. The circumstances of this case related to a permit for one of San Francisco’s wastewater treatment facilities, which discharges into the Pacific Ocean. In 2019, EPA had imposed two new requirements on the permit: a prohibition on any discharges that “contribute to a violation of any applicable water quality standard” for receiving waters (i.e., the Pacific Ocean); and a prohibition on any treatment or discharge that “create[s] pollution, contamination, or nuisance as defined by” a provision of the California Water Code. The Supreme Court ruled that EPA exceeded its authority by placing these provisions into the permit, explaining that EPA has authority to impose “limitations” that are necessary to meet water quality standards, but not to simply require that the water quality standards themselves be met. The Court emphasized that it is the permit writer’s job to determine what specific steps a permittee must take to ensure water quality. This decision should provide greater clarity to permit holders by requiring clear compliance standards in NPDES permits.
Seven County Infrastructure Coalition v. Eagle County, Colorado, 145 S. Ct. 1497 (2025)
As we reported in June, in an opinion authored by Justice Kavanaugh, the Court held that the D.C. Circuit had failed to give the substantial deference owed to federal agencies when they issue environmental impact statements (EIS) under the National Environmental Policy Act (NEPA). In addition, the Court ruled that the D.C. Circuit improperly had required the agency to consider the environmental impacts of projects “separate in time and place” from the specific project being evaluated by the agency. On the specific facts of the case, the agency had approved the construction and operation of an 88-mile stretch of railroad to transport crude oil, and the lower court faulted the agency for not having considered the effects of increased oil drilling and refining. The Court took the opportunity to emphasize that some courts have engaged in “overly intrusive” review of agency EISs, allowing NEPA to become a tool used to stop or slow down projects. This decision should help sharpen the scope of the “project” under NEPA review and tamp down on efforts by project opponents to bring broader environmental issues into the analysis of a project’s impacts.
EPA v. Calumet Shreveport Refining, LLC, 145 S. Ct. 1735 (2025)
In a 7-2 decision, the Court clarified the two-step framework for determining venue under the Clean Air Act (CAA) and, applying that framework, concluded that the dispute before it belonged in the D.C. Circuit. The case involved challenges brought by several small refineries to EPA’s denial of their petitions to be granted exemptions from the CAA’s renewable fuel program. The EPA had asserted these challenges must be brought in the D.C. Circuit because the denials were “nationally applicable” actions, given that EPA had aggregated numerous similar petitions and collectively denied them. The Supreme Court rejected this position, concluding that the “action” at issue in each petition involved only the petitioning refinery and thus was “locally or regionally applicable.” But the Court agreed with EPA’s alternative position that its denials nevertheless were “based on a determination of nationwide scope or effect,” and therefore venue in the D.C. Circuit was proper. Justice Gorsuch, in a dissent joined by the Chief Justice, criticized the Court’s “new” test for determining venue under the CAA and predicted that it is “likely to render simple venue questions unnecessarily difficult and expensive to resolve.” More details can be found in our blog post on this case.
Diamond Alternative Energy, LLC v. EPA, 145 S. Ct. 2121 (2025)
In this case, which we reported on in June, the Court concluded that the petitioners, a group of fuel producers, had standing to challenge EPA’s approval of California regulations requiring automakers to produce fewer gas-powered vehicles and more electric vehicles. The sole legal issue concerned the “redressability” prong of the standing inquiry; namely, whether a judgment in the fuel producers’ favor would redress their asserted injury. The fuel producers argued that the California regulations would reduce the number of gas-powered cars on the road, leading to a decrease in fuel sales. In response, the EPA and California maintained that even in the absence of the regulations, consumer demand for electric vehicles would exceed the manufacturing level required by the regulations, so invalidating the regulations would not increase fuel sales. The Court concluded that “commonsense economic principles support the fuel producers’ standing,” reasoning that the regulations were likely to cause at least some reduction in demand for fuel, so their invalidation would redress the fuel producers’ economic injury. And the Court emphasized that the very purpose of the regulations was to reduce the use of gasoline. Based on this reasoning, the Court rejected EPA and California’s contention that the fuel producers should have introduced more evidence, such as affidavits from expert economists; “to show redressability, the plaintiff must simply ‘show a predictable chain of events’ that would likely result from judicial relief and redress the plaintiff’s injury.”
Cases To Be Decided in 2026
Chevron USA Inc. v. Plaquemines Parish, Louisiana (No. 24-813)
Several Louisiana parishes sued Chevron in state court, seeking to hold the company liable under Louisiana’s State and Local Coastal Resources Management Act of 1978 for damages allegedly resulting from the company’s past oil exploration and production activities. Chevron removed the challenges to federal court on the basis that those activities were conducted under contracts with the federal government, invoking the federal-officer removal statute. The federal district court remanded to state court and the Fifth Circuit affirmed. The Supreme Court will address whether, following a 2011 amendment to the federal-officer removal statute, the removing party must show a causal connection between the lawsuit and an act performed under the direction of the federal government rather than merely demonstrating that the suit is related to such an act. During oral arguments heard on January 12, 2026, several justices questioned the potentially sweeping scope of removal advocated by Chevron and by the United States, which offered argument in support of Chevron’s reading of the removal statute. With Justice Alito recused due to a financial conflict, it remains to be seen how the remaining eight justices will rule.
Galette v. New Jersey Transit Corporation (No. 24-1021)
In this consolidated appeal from decisions by the highest courts of Pennsylvania and New York, the Court will consider whether the New Jersey Transit Corporation is an arm of the State of New Jersey for interstate sovereign immunity purposes. Two separate tort lawsuits were filed against NJ Transit, one in Pennsylvania and the other in New York. The Supreme Court of Pennsylvania recognized NJ Transit as an arm of New Jersey and held that sovereign immunity barred suit. But the New York Court of Appeals reached the opposite conclusion. This appeal may offer the U.S. Supreme Court an opportunity to clarify the analysis that determines when state-created entities enjoy sovereign immunity from suit in the courts of other states. The Court heard oral arguments on January 14, 2026. Although several justices were skeptical of New Jersey’s argument that NJ Transit, which was established as a corporation, could nevertheless be considered part of the State of New Jersey based on a multifactor test, there ultimately was no clear indication how the Court will come out on the question.
Pending Petitions for Certiorari
Suncor Energy Inc. v. County Commissioners of Boulder County (No. 25-170)
Petitioners are energy companies that produce and sell fossil fuels, who seek review of a decision of the Colorado Supreme Court that allowed common-law tort claims for climate-change-related harms to advance. Petitioners contend that these state-law claims are preempted by federal law because the claims relate to harms allegedly caused by interstate and international greenhouse gas emissions and their effect on the global climate. If the Court were to take up this petition, it may signal that there are at least four justices interested in entertaining some version of petitioners’ preemption theory, which could significantly curtail the many and various ongoing efforts to seek remedies for climate-change-related harms in state courts across the country. It is not clear to what extent EPA’s proposed decision to rescind the 2009 Endangerment Finding could impact the preemption analysis. The petition was distributed for the Court’s conference of January 16, 2026.
Monsanto Co. v. Salas & Monsanto Co. v. Durnell & Monsanto Co. v. Johnson (Nos. 24-1068 & 1097 & 1098)
As stated by petitioner Monsanto, the question presented by these petitions is whether the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) “preempts a state-law failure-to warn claim where EPA has repeatedly concluded that the warning is not required, and the warning cannot be added to a product without EPA approval.” On January 16, 2026, the Court granted the petition in the Durnell case, which stems from a state-court trial verdict in favor of plaintiff-respondent John Durnell, who claimed that exposure to Roundup caused his non-Hodgkin’s lymphoma. The Court granted Monsanto’s petition limited to the following rephrased question: “Whether the Federal Insecticide, Fungicide, and Rodenticide Act preempts a label-based failure-to-warn claim where EPA has not required the warning.” The case will be argued during the spring of 2026.
Whitmer v. Enbridge Energy, LP (No. 25-582)
As stated by petitioner, the Governor of the State of Michigan, the question presented by this petition is “[w]hether a State is the real party in interest, and therefore entitled to sovereign immunity, where a private plaintiff sues state officials in federal court for relief that would diminish, but not necessarily extinguish, the State’s ownership and control of its sovereign lands.” The case stems from Michigan’s revocation and termination of an easement that had allowed an energy company to construct and operate pipelines on state lands located beneath navigable waters. The easement holder sued state officials, seeking an order preventing state officials from impeding the operation of its pipelines, and the U.S. Court of Appeals for the Sixth Circuit allowed the lawsuit to proceed. The court of appeals concluded that state sovereign immunity did not apply because the energy company’s requested relief would not completely divest the State of ownership and regulatory control over the lands. In its petition for certiorari, Michigan maintains that this case presents an opportunity for the Supreme Court to resolve a circuit split regarding whether the Ex parte Young doctrine allows lawsuits to proceed in federal court when the sought-after relief would diminish, but not completely extinguish, a state’s ownership and control over lands. As of January 15, 2026, briefing on the petition had not yet concluded.
Recently Denied Petitions for Certiorari
Alaska v. United States (No. 25-320)
On January 12, 2026, the Court denied Alaska’s petition for certiorari, which sought review of “[w]hether the United States can regulate fishing on Alaska’s navigable waters under the Alaska National Interest Lands Conservation Act, when its statutory authority is limited to ‘public lands’ and that term is defined as ‘lands, waters, and interests therein...the title to which is in the United States.’” The dispute stemmed from Alaska’s effort to open certain waters to gillnet fishers who are not federally qualified rural subsistence fishers, and the United States’ lawsuit to stop Alaska from doing so. The Court’s denial of Alaska’s petition leaves in place the decision of the U.S. Court of Appeals for the Ninth Circuit siding with the federal government regarding the proper interpretation of “public lands” under the Alaska National Interest Lands Conservation Act.
United National Foods, Inc. v. National Labor Relations Board (No. 25-369)
Although not an environmental case, this petition raised questions about how courts should apply the Supreme Court’s recent Loper Bright decision, which overturned the Chevron deference doctrine, as well as issues regarding the precedential value of judicial decisions that applied Chevron prior to Loper Bright. The case previously was before the Supreme Court, in 2024; in a summary order, the Court vacated a prior decision of the U.S. Court of Appeals for the Fifth Circuit and remanded to that court for further consideration in light of Loper Bright. Upon remand, the Fifth Circuit reached the same conclusion as it had previously, namely that the National Labor Relations Board (NLRB) had acted within its authority when it determined that NLRB’s acting general counsel had discretion to withdraw a complaint filed against certain labor unions. In doing so, the Fifth Circuit considered a relevant pre-Loper Bright Supreme Court precedent and observed that the decision “remains good law.” In its petition for certiorari, United National Foods contended that the Fifth Circuit upon remand did not faithfully apply the independent judicial statutory inquiry required under Loper Bright and improperly relied upon pre-Loper Bright precedent.
The Court denied the petition on January 12, 2026.
Shelby County v. Couser (No. 25-419)
As stated by petitioner Shelby County and other local government entities and officials, the question presented by this petition was “[w]hether a state or local law regulating the location or routing of an interstate pipeline is a preempted ‘safety standard’ under the Pipeline Safety Act when a court concludes that the law was primarily motivated by safety concerns.” The Court denied the petition on January 12, 2026, leaving in place the decision by the U.S. Court of Appeals for the Eighth Circuit, which concluded that the Pipeline Safety Act preempted certain local ordinances regulating pipelines.
