A district court granted in part and denied in part environmental groups' motion for a temporary restraining order (TRO) in a challenge to the federal government's construction and operation of a mass immigrant detention and deportation facility in the Florida Everglades. The groups argued construction and operation of the project without any environmental review violated NEPA, and sought to enjoin the state of Florida and the federal government from developing or using the site as a detention facility until the government complies. A few weeks after the suit was filed, the facility completed its first phase of construction and ongoing operations, and the groups sought a TRO to halt further construction, pause transportation of additional detainees to the site, and cease operations related to detaining or preparing to detain anyone not already there. The court found that the government's control over the facility's operations, evidence that construction was at the request of the Department of Homeland Security, and regular inspections by Immigration and Customs Enforcement officials, combined with the undisputed lack of any prior environmental assessment, created a sufficient likelihood of success on the groups' claim. It further found the balance of equities and public interest favored granting a TRO because the harm to the government from briefly suspending expansion of the facility was minimal and was not preventing continued operations there nor additional detainees from being brought there if current capacity allowed; but that if the facility were expanded, it would be difficult to change course. The court entered a TRO prohibiting Florida and the federal government from installing new industrial-style lighting; doing any paving, filling, excavating, or fencing; or doing any other expansion, including placing or erecting additional buildings, tents, dormitories, or other residential or administrative buildings on the site, until the court enters an order as to the groups' motion for preliminary injunction.

A district court ruled for environmental groups in a challenge to FWS' 2024 finding that listing a distinct population segment (DPS) of gray wolves in the western United States under the ESA was not warranted. The groups argued FWS failed to consider a "significant portion" of the gray wolf's range by ignoring historical range and discounting both Colorado and the West Coast, failed to consider the best available science on gray wolf populations and the impacts of human-caused mortality, and failed to evaluate the threat to gray wolves from inadequate existing regulatory mechanisms. The court found FWS' interpretation of "range" to categorically include only a species' current or occupied range was contrary to the Act, that the Service failed to adequately explain why it relied extensively on Colorado's future contributions to the western DPS while also discounting its significance on purely quantitative grounds, and that its determination that the gray wolf in the West Coast area was not likely in danger of extinction in the foreseeable future was contrary to the record evidence. The court further found FWS failed to use the best available science by relying on population estimates for Idaho and Montana without addressing criticisms raised, and that the Service failed to consider the possibility that states could not hold their commitment to a minimum wolf population. It vacated and remanded FWS' finding.

A district court denied business groups' motion to preliminarily enjoin two California laws that require large businesses to disclose their greenhouse gas emissions (S.B. 253) and climate-related financial risk (S.B. 261). The groups challenged the laws on First Amendment grounds. The court found the groups did not show a likelihood of success as to their challenge to S.B. 253, given California's duel interests in providing reliable information on which to make investment decisions and in reducing emissions; nor did they show a likelihood that the state's interest in providing reliable information to investors failed intermediate scrutiny in a substantial majority of S.B. 261's applications. It further found the balance of equities did not favor the groups because enjoining the laws would delay the state from advancing the public interests for which it adopted them. The court denied the motion.

A district court denied environmental groups' motion for summary judgment in a challenge to a 2019 EPA rule that exempted air emissions from animal waste from an EPCRA reporting requirement. The groups argued the rule contravened EPCRA by concluding animal waste emissions were no longer reportable under §304(a)(2) following their 2018 exemption from CERCLA's notification requirements via the Fair Agricultural Reporting Method (FARM) Act, that EPA failed to consider the public's right to access information and changed course without explanation, and that EPA violated NEPA by failing to conduct an environmental impact analysis. The court found that CERCLA's exemption for air emissions from animal waste at farms—which targets the "nature" of such releases, or the "way in which" releases happen—meant that such releases "do not occur" in a manner that requires CERCLA §103(a) reporting for purposes of EPCRA §304(a)(2). It further found the rule was not arbitrary or capricious because it was consistent with the best reading of §304(a)(2) and provided a reasoned explanation for exempting the emissions. The court also found EPA was not obligated to consider environmental information because it was compelled by the FARM Act to issue the rule. The court denied the groups' motion for summary judgment and granted EPA's cross-motion.

A district court granted summary judgment for cultural and environmental groups in a challenge to a letter NMFS sent to fishing permit holders informing them that commercial fishing was no longer prohibited in certain areas of the Pacific Islands Heritage Marine National Monument following a presidential proclamation. The groups argued NMFS violated the Magnuson-Stevens Fishery Conservation and Management Act and the APA by failing to engage in notice-and-comment rulemaking before sending the letter. The court found the letter constituted final agency action because it created a safe harbor for commercial fishing operations by announcing a firm agency commitment to nonenforcement, and thus carried significant legal consequences. It further found NMFS chose not to advance an argument that the letter was an interpretive rule rather than a legislative one, and thus forfeited any argument that notice-and-comment procedures were unnecessary. It granted summary judgment for the groups and vacated the letter.

A district court granted FWS' motion to vacate and remand its 2022 rule listing the northern distinct population segment (DPS) lesser prairie-chicken as threatened and the southern DPS of the species as endangered. Texas, Oklahoma, Kansas, and an oil and gas group sued FWS, arguing it improperly applied its policy for determining DPSs in violation of the ESA. Following the change in federal administration in January 2025, FWS reevaluated the plaintiffs' claims and determined that it erred in applying the DPS policy and did not provide sufficient justification that the two population segments were significant; it moved for voluntary vacatur and remand of the rule. The court found FWS conceded the rule was unlawful and that its vacatur request comported with APA requirements that agency action found to be "arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with the law" to be set aside. It further found FWS' concessions pointed to a serious, foundational defect in the rule that could not be resolved by remand alone. It vacated and remanded the rule.

A district court granted an environmental group's motion for preliminary injunction in a CWA citizen suit brought against a chemical manufacturer for discharging per- and polyfluoroalkyl substances into the Ohio River. The group argued the discharges violated effluent standards and limitations set by the permit. The manufacturer moved to dismiss. The court found the group demonstrated that the unpermitted discharge irreparably harmed its members and the public, that the manufacturer knew it was violating its permit and intended to continue violating it, and that equity did not protect continued commission of a statutory wrong. The court granted the motion and ordered the manufacturer to comply with its permit.

The Second Circuit vacated a district court's dismissal of a lawsuit concerning a product that disables motor vehicle emissions controls. The federal government sued the company that manufactured and sold the product, arguing it violated the CAA by manufacturing and selling a "defeat device." The company moved to dismiss, arguing the product was not prohibited by the CAA and that it was immune from liability under §230 of the Communications Decency Act because it published, but did not write, the software that disabled the relevant emissions controls and the product allowed users to access and implement the third-party software in their cars. The district court concluded the government sufficiently alleged that the product was a defeat device, but granted the motion to dismiss on the basis of §230 immunity. The appellate court agreed that the product was a defeat device, but concluded that the government adequately alleged the company "directly and materially contributed to" the creation of the software and was ineligible for §230 immunity. It vacated the dismissal on immunity grounds and remanded for further proceedings.

The Ninth Circuit affirmed summary judgment for the federal government in a lawsuit seeking to preclude the state of Alaska from interfering with federal efforts to ban gillnet fishing for non-rural subsistence users in the Kuskokwim River pursuant to a rural subsistence priority established under the Alaska National Interest Lands Conservation Act (ANILCA). In 2021 and 2022, the manager of the Yukon Delta National Wildlife Refuge closed parts of the river to gillnet fishing, but provided exceptions for federally qualified rural subsistence users on specified days. Alaska's Department of Fish and Game then asserted authority over the entire river by purporting to authorize gillnet fishing by all subsistence users. The government sued the state, arguing it held reserved water rights to the stretch of river within the refuge based on precedent known as the Katie John trilogy, which held that "public lands" in Title I of ANILCA included navigable waters in which the United States held reserved water rights. Alaska countered that Katie John was irreconcilable with Sturgeon v. Frost, 587 U.S. 28 (2019), in which the Supreme Court declined to so interpret the term. A district court concluded Katie John was not irreconcilable with Sturgeon, and granted summary judgment for the government. The appellate court held that the decisions could be harmonized on the ground that the distinct context and statutory objective of Title VII of ANILCA called for an interpretation that included navigable waters where subsistence fishing has traditionally taken place. Moreover, Congress passed appropriations that signaled its approval of that interpretation for purposes of Title VII. The court affirmed summary judgment for the government.

The Tenth Circuit granted in part and denied in part a challenge to EPA's approval of Colorado's 2019 SIP revisions. An environmental group argued the revisions, which changed the wording of a permit requirement for new emission sources and added to the definition of a key threshold to evaluate compliance, prevented regulators from blocking construction when a new source would generate excessive emissions and allowed them to disregard emissions during drilling, fracking, and well completion. The court concluded the group did not show an effect from the revised wording in the permit requirement, but found that EPA acted arbitrarily and capriciously by failing to address the potential emissions during drilling, fracking, and well completion. It denied the petition as to the revised permit requirement, but granted it as to the revised definition of "commencement of operation" and remanded to EPA for further explanation.