Last month in Chamber of Commerce of the United States of America et al. v. United States Environmental Protection Agency, the D.C. Circuit Court of Appeals denied petitions for review of the United States Environmental Protection Agency’s (“EPA’s” or the “Agency’s”) May 2024 designation of two per- and polyfluoroalkyl substances (“PFAS”) chemicals—perfluorooctanoic acid (“PFOA”) and perfluorooctanesulfonic acid (“PFOS”)—as “hazardous substances” (the “Designation”) under the Comprehensive Environmental Response, Compensation, and Liability Act (“CERCLA” or the “Act”).  The petitions were filed by industry interest groups that use, transport, or discharge PFOA and PFOS (the “Petitioners”).  Read More »

Share | Email| Comments|  Topics: Administrative Procedures Act, Agency Action, CERCLA, Contamination, D.C. Circuit, EPA, Loper Bright, PFAS, Pollutants, Potentially Responsible Parties, Rulemaking, Water

The U.S. Court of Appeals for the Tenth Circuit issued a decision on August 3, 2026, which clarified the scope of the diligent prosecution bar to citizen suits under the Clean Air Act (“CAA”).  The decision was a partial victory for the environmental organizations that brought the lawsuit and adds to the body of appellate decisions aiming to elucidate this heavily litigated area of the law. Read More »

Share | Email| Comments|  Topics: Air, CERCLA, Citizen Suit, Citizens Suit, Clean Air Act, Colorado, Consent Decree, Diligent Prosecution, Emissions, EPA, Loper Bright, Pollutants, Superfund, Tenth Circuit

Earlier this month, the U.S. Court of Appeals for the Eleventh Circuit held in City of Brunswick v. Honeywell International, Inc., 2026 WL 2224648 (11th Cir. Aug. 3, 2026), that potentially responsible parties (“PRPs”) implementing an EPA-selected CERCLA remedy pursuant to a consent decree may be “acting under” a federal officer for purposes of the federal officer removal statute, 28 U.S.C. § 1442(a)(1). The decision may provide a basis for such PRPs to remove related state-law claims to federal court. The decision also holds that an appeal of a remand order involving federal officer removal automatically stays district court proceedings, including the remand order, pending appeal. Read More »

Share | Email| Comments|  Topics: Causation, CERCLA, Cleanup, Consent Decree, Contamination, Eleventh Circuit, EPA, Federal Jurisdiction, Potentially Responsible Parties, Preemption, Remediation, Removal, Subject Matter Jurisdiction, Superfund

On June 25, 2026, the United States Supreme Court issued a significant preemption decision in Monsanto Co. v. Durnell, holding that the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”) preempts state-law failure-to-warn claims that would require cancer warnings on Roundup’s label beyond those approved by the U.S. Environmental Protection Agency (“EPA”). In a 7-2 opinion by Justice Kavanaugh, the Court reversed a Missouri judgment awarding more than $1 million to plaintiff John Durnell, who alleged that Monsanto’s Roundup caused his cancer and should have included a cancer warning. Read More »

Share | Email| Comments|  Topics: EPA, Federal Insecticide, Fungicide, and Rodenticide Act, FIFRA, Supreme Court, Toxic Torts, United States Supreme Court

In a recent decision by the United States Court of Appeals for the Sixth Circuit, Sierra Club v. EPA, Nos. 23-3581/3583 (6th Cir. Dec. 5, 2025), the Court invoked its statutory interpretation authority to hold that EPA contravened the plain language of the Clean Air Act (“CAA”) by redesignating the Detroit area as in attainment with the 2015 ozone National Ambient Air Quality Standards (“NAAQS”). Conversely, the Court deferred to EPA’s technical expertise in determining that certain air emissions should be excluded from consideration of the Detroit area’s compliance with the ozone NAAQS because of their qualification as “exceptional events” under the CAA, demonstrating that Courts will continue to defer to agencies’ expertise, but will not defer to agency interpretations of their enabling statutes. Read More »

Share | Email| Comments|  Topics: Agency Action, Air, Chevron Deference, Clean Air Act, Emissions, EPA, Hazardous Air Pollutants, Loper Bright, Michigan, Sixth Circuit

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. Read More »

Share | Email| Comments|  Topics: Agency Action, Air, Clean Air Act, D.C. Circuit, EPA, Federal Procedure, Procedure, Refinery, Renewable Fuel Standard, State Implementation Plans, Supreme Court, United States Supreme Court, Venue

On June 20, 2025, the Supreme Court issued it opinion in Diamond Alternative Energy v. EPA, holding fuel producers had standing—and had specifically demonstrated redressability—to challenge California-specific regulations EPA approved under the Clean Air Act.  The Court’s opinion  reversing and remanding to the D.C. Circuit left the merits of the case for another day, but acknowledged that the regulations at issue may be rescinded shortly, mooting most, if not all, of the parties’ controversy. Read More »

Share | Email| Comments|  Topics: Agency Action, Air, California, Clean Air Act, Climate Change, D.C. Circuit, Emissions, EPA, Federal Procedure, Greenhouse Gas, Legislation, Oil and Gas, Standing, Supreme Court, United States Supreme Court

In the wake of the Supreme Court’s decision in Loper Bright Enters. v. Raimondo, 244 S.Ct. 2244 (2024), the general breadth and scope of agency decision-making has been called into question. In its recent decision, Huntsman Petrochemical LLC v. EPA, No. 23-1045, 2024 WL 3763355 (D.C. Cir. Aug. 13, 2024), the D.C. Circuit has made it clear that where statutory interpretation is not implicated, the Court will continue to afford EPA’s conclusions involving technical expertise a significant degree of deference. While neither the parties nor the Court attempted to address or reference Loper Bright, the Court articulated a clear standard applicable to agency actions involving statistical and modeling analyses: the Court will examine each step of an agency’s analysis to satisfy themselves that the agency has not “departed from a rational course.” Only where a statistical model “bears no rational relationship to the characteristics of data to which it was applied” will agency action be deemed arbitrary and capricious. Accordingly, regulated entities should be aware that the concept of deference lives on when challenging agency decision-making, even in the wake of the fall of Chevron Deference. Read More »

Share | Email| Comments|  Topics: Air, Chevron Deference, Clean Air Act, D.C. Circuit, Emissions, EPA, HAPs, Hazardous Air Pollutants, Rulemaking

In Sackett v. EPA, 2023 WL 3632751 (U.S. May 23, 2023), the Supreme Court limited the authority of the United States Environmental Protection Agency (“EPA”) to regulate wetlands by embracing a “continuous surface connection test” to determine if adjacent wetlands are subject to the Clean Water Act (“CWA”) and explicitly rejecting Justice Kennedy’s “significant nexus” test from Rapanos v. United States, 547 U.S. 715, 754 (2006). While the 9-0 decision was unanimous in judgment by holding that the Sacketts’ wetland was not subject to federal jurisdiction, the court was sharply divided as to the test to determine when an adjacent wetland qualifies as a Water of the United States (or “WOTUS”).  A five-justice majority held that the CWA’s jurisdiction includes only adjacent wetlands that are indistinguishable from WOTUS due to a continuous surface connection. Under this framework, for an adjacent wetland to be subject to CWA jurisdiction, the adjacent body of water must constitute a WOTUS, and the adjacent wetland must have a continuous surface connection with the WOTUS such that it is difficult to determine where the body of water ends and the wetland begins.  The majority’s holding casts serious doubt on the continuing viability on the final WOTUS rule that became effective earlier this year and relied in part on the “significant nexus” test that EPA and the United States Army Corps have applied through guidance since the Rapanos decision. See 88 Fed. Reg. 3004 (Jan. 18, 2023). Read More »

Share | Email| Comments|  Topics: Clean Water Act, Decisions of Note, EPA, Major Questions Doctrine, Navigability, Ninth Circuit, Rapanos, Supreme Court, United States Supreme Court, Wetlands

EPA’s Clean Air Act (“CAA”) rulemakings directed at power plants are often the target of regulatory challenges in federal court.  EPA’s latest rulemaking regulating Hazardous Air Pollutant (“HAP”) emissions from coal- and oil-fired electric utility steam generating units (“EGUs”) is unlikely to be an exception. 88 Fed. Reg. 13956 (Mar. 6, 2023).  In the now final rule, EPA has revoked an earlier action taken in 2020, in which the agency declined to regulate HAP emissions from EGUs after comparing the costs of compliance relative to the benefits of regulation, relying at the time on the Supreme Court’s decision in Michigan v. EPA, 576 U.S. 743 (2015).  Id. at 13957; see also 85 Fed. Reg. 31286. Now, just three years later under a new administration, the agency has backtracked, finding that it is appropriate and necessary to regulate HAP emissions from EGUs based on new data regarding the costs and benefits of regulating HAP emissions.  EPA claims that its latest decision is actually more in line with the statutory factors identified in Michigan for determining whether it is “appropriate and necessary” to regulate HAP emissions from EGUs under the CAA. Read More »

Share | Email| Comments|  Topics: Air, Clean Air Act, EPA, HAPs, Hazardous Air Pollutants, Rulemaking