On July 14, 2026, the United States Fish and Wildlife Service (“FWS”) together with the National Marine Fisheries Service (“NMFS”) (collectively, “the Services”) finalized a rule to rescind the regulatory definition of “harm” under the Endangered Species Act (“ESA”). The term is part of the ESA’s overall prohibition on “take” of protected wildlife and a regulatory definition for the term had been in place since 1975. In rescinding the rule, the Services assert that the definition of “harm” does not match the best possible interpretation of the ESA. Since the rule was finalized, at least four federal lawsuits have been filed by environmental groups and Native American Tribes, claiming that rescinding the definition violates federal law. Both the decision to rescind the regulatory definition of “harm” and the lawsuits challenging it are likely to impact how the ESA is implemented going forward.
The ESA & Definition of “Harm”
The ESA was enacted by Congress and signed by the President in 1973 and is jointly administered by the Services. According to Congress, the purpose of the ESA is to “provide a means whereby the ecosystems upon which endangered species and threatened species depend may be conserved” and to “provide a program for the conservation of such endangered [and] threatened species.” 16 U.S.C. § 1531(b). To help achieve that purpose, the ESA prohibits the “take” of any wildlife species that has been identified by the Services as either threatened or endangered. 16 U.S.C. § 1538(a)(1)(B). The term “take” is defined as “to harass, harm, pursue, hunt, shoot, wound, trap, capture, or collect, or to attempt to engage in any such conduct.” 16 U.S.C. § 1532(19).
FWS first issued a regulatory definition of the word “harm” as it appears in the definition of “take” in 1975. In that initial regulation, FWS defined “harm” as “an act or omission which actually injures or kills wildlife, including acts which annoy it to such an extent as to significantly disrupt essential behavior patterns, which include, but are not limited to, breeding, feeding, or sheltering; [and] significant environmental modification or degradation which has such effects[.]” 40 F.R. 44412. In 1981, FWS modified the definition so that “harm” meant “an act which actually kills or injures wildlife [including] significant habitat modification or degradation where it actually kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding or sheltering.” 46 F.R. 54748. NMFS adopted the same definition of “harm” in 1999. Both Services have retained the definition unchanged until 2026.
By defining “harm” to include “significant habitat modification or degradation” that “actually kills or injures wildlife,” the Services interpreted the prohibition on “take” of protected species to include destruction of species habitat even if habitat destruction did not involve directly killing or injuring a member of the species. For example, under the 1981 definition of “harm,” it would be a violation of the ESA to cut down a stand of trees that provide habitat to an endangered species of bird even if none were directly killed when the trees were cut down.
In 1995, the United States Supreme Court issued Babbitt v. Sweet Home Chapter of Communities for A Great Oregon, 515 U.S. 687 (1995) where the Court upheld FWS’s “harm” definition. The case was initially filed by a coalition of landowners and logging companies who challenged the validity of the “harm” definition and its inclusion of habitat modification and degradation. The groups argued that Congress did not intend the word “take” to include habitat modification and that instead “harm” should be limited to direct applications of force against protected species. Ultimately, the Court disagreed and upheld the FWS definition of “harm” in a 6-3 opinion authored by Justice Stevens. The majority stated that the text of the ESA promoted the conclusion that the “harm” definition was reasonable. According to the Court, the “broad purpose” of the ESA to protect endangered and threatened wildlife supported including habitat modification in the meaning of “take.” Because the Court concluded that the FWS definition of “harm” was reasonable, it relied on Chevron deference to allow the definition to stand. Chevron deference comes from the Supreme Court case Chevron U.S.A. Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837 (1984). There, the Court held that when judges are asked to consider the legality of an agency regulation that interprets ambiguous statutory language, the reviewing court should defer to the agency interpretation if the court concludes that it is reasonable understanding of the statute.
Along with a majority opinion, the Supreme Court in Babbitt v. Sweet Home also issued a dissent authored by Justice Scalia. In that dissent, Justice Scalia agreed with the groups who brought the lawsuit and would have limited the definition of “harm” to acts that directly kill or injure protected wildlife. According to Justice Scalia, limiting “harm” to direct acts against wildlife makes sense when looking at the statutory definition of “take” which includes other direct actions like pursue, hunt, shoot, and wound. However, a majority of the Supreme Court rejected this argument, reasoning that if “wound” and “harm” were both intended to refer to direct injuries to wildlife, it would not make sense for Congress to include both words in the “take” definition.
The Recission Rule
On April 17, 2025, the Services published a joint proposal in the Federal Register to rescind the regulatory definition of “harm.” According to the Services, defining “harm” to include habitat modification does not match “the single, best meaning” of the ESA. Instead of adopting a new definition, the Services proposed to instead take up the position articulated by Justice Scalia in his Babbit v. Sweet Home dissent and limit their understanding of “harm” to actions that directly kill or injure protected species.
The Services explained that their decision to rescind the “harm” definition was prompted by the Supreme Court’s ruling in Loper Bright Enters. v. Raimondo, 603 U.S. 369 (2024) where the Court overturned the doctrine of Chevron deference. Instead of deferring to reasonable agency interpretations of ambiguous statutory language, the Supreme Court held that there is a “single, best meaning” of the law and that it is up to courts to determine what the law means. A full breakdown of the Court’s ruling is available here. When the Court issued Loper Bright v. Raimondo, it recognized that many of its previous holdings were based on Chevron deference. The Court noted that those cases were still good law and that past decisions should not be considered invalid or overturned because of the Court’s Loper Bright v. Raimondo decision.
In their proposal to rescind the “harm” definition, the Services acknowledged that the Supreme Court held that prior cases that were resolved under the Chevron framework, such as Babbitt v. Sweet Home, were still good law. However, the Services noted that as part of the Executive Branch, they have a constitutional responsibility to “take care that the laws be faithfully executed.” Because the Services believe that the single, best interpretation of the ESA’s “take” prohibition was given by Justice Scalia in his Babbit v. Sweet Home dissent, they proposed to rescind the “harm” definition and limit “take” to actions that directly kill or injure protected species.
The Services opened a 30-day period of public comment on the proposed Recission Rule through April 17, 2025. After reviewing all the comments they received, the Services issued a final Recission Rule on July 14, 2026. In that final rule, the Services completely rescinded the ESA regulatory definition of “harm.” Although they did not adopt a new definition, the Services clarified that habitat modification and degradation would no longer be considered “take” for purposes of the ESA. The rule is set to go into effect on September 14, 2026.
Legal Challenges
The same day the Recission Rule was finalized, three federal lawsuits were filed to challenge the decision. A fourth was filed days after. The plaintiffs in Swinomish Indian Tribal Cmty. v. Nat’l Marine Fisheries Serv., No. 2:26-cv-0247 (July 14, 2026, W.D. Wash.), Envt’l Protection Info. Ctr. v. Nat’l Marine Fisheries Serv., No. 3:26-cv-07176 (July 14, 2026, N.D. Cal.), Ctr. for Biological Diversity v. Burgum, No. 2:26-cv-02474 (July 14, 2026, W.D. Wash.), and Nat’l Wildlife Fed’n v. U.S. Fish and Wildlife Serv., No. 2:26-cv-02897 (July 17, 2026, D. S.C.) all claim that the Recission Rule violates the Administrative Procedure Act (“APA”) and the National Environmental Policy Act (“NEPA”). All four lawsuits ask that the Recission Rule be reversed and the “harm” definition be reinstated.
APA Claim
All four lawsuits allege that the Recission Rule violates the APA because the Services did not provide a “reasonable rationale” for rescinding the “harm” definition. The APA is a federal law that governs how agencies draft and adopt regulations. Under the APA, courts are required to “hold unlawful and set aside agency actions, findings, and conclusions found to be arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.” 5 U.S.C. § 706(2)(A). The Supreme Court has held that a regulation is arbitrary and capricious under the APA if an agency fails to provide a reasonable explanation to support its decision.
The plaintiffs in the four cases argue that the Recission Rule violates the APA’s “arbitrary and capricious” standard because the only explanation the Services provided to support rescinding the “harm” definition is an improper interpretation of Loper Bright v. Raimondo. The plaintiffs argue that under the Loper Bright standard, it is courts, not agencies, that determine the single, best interpretation of the law. Additionally, the plaintiffs claim that the ESA interpretation the Services have adopted in the Recission Rule cannot be the best interpretation because it is one that the Supreme Court has rejected. The plaintiffs assert that because Justice Scalia wrote in dissent in Babbitt v. Sweet Home, his interpretation was considered by the Court and found not to be the best interpretation of the ESA. According to the plaintiffs, the Services failed to explain how or why Justice Scalia’s dissent, rather than the majority, articulates the “single, best” meaning of “take” under the ESA. For that reason, the plaintiffs argue that adopting Justice Scalia’s position in the Recission Rule is “arbitrary and capricious” in violation of the APA.
NEPA Claim
NEPA was enacted in 1970 to “encourage productive and enjoyable harmony between man and his environment[.]” 43 U.S.C. § 4321. To help achieve that goal, NEPA requires federal agencies to prepare a “detailed statement” for any “major federal actions” that significantly affect the quality of the human environment. 42 U.S.C. § 4332(C). These statements, known as Environmental Impact Statements (“EIS”) must describe any “reasonably foreseeable environmental effects of the proposed agency action[.]” The term “major federal action” is broadly defined under NEPA to include any “action that […] is subject to substantial federal control and responsibility.” 42 U.S.C. § 4336e(10)(A).
An agency can forgo preparing an EIS for a particular action if it finds that the action falls within an identified “categorical exclusion.” 42 U.S.C. § 4366(a)(2). The term “categorical exclusion” refers to categories of actions that a federal agency has determined do not significantly affect the environment and therefore do not require review under NEPA. 42 U.S.C. § 4336e(1). NEPA allows agencies to either adopt their own list of categorical exclusions or to rely on categorical exclusions established by another agency provided all requirements are met. 42 U.S.C. § 4336c.
The Services determined that the Recission Rule did not require an EIS after concluding that it fell under a categorical exclusion that exempts from NEPA review policies and regulations “that are of an administrative, financial, legal, technical, or procedural nature; or whose environmental effects are too broad, speculative, or conjectural to lend themselves to meaningful analysis[.]” 43 C.F.R. § 46.210(i). The Services reasoned that the categorical exclusion was appropriate because they had used the same categorical exclusion to determine that previous rulemaking efforts to adopt and then rescind a definition of “habitat” were not subject to NEPA review.
In all four legal challenges, the plaintiffs argue that the Services violated NEPA by misapplying a categorical exclusion to the Recission Rule when they should have prepared an EIS. The plaintiffs note that the categorical exclusion applied to the Recission Rule may not be used for actions that “[h]ave significant impacts on species listed, or proposed to be listed, on the List of Endangered or Threatened Species[.]” 43 C.F.R. § 46.210; § 46.215(g). Because changing the definition of “harm” within the ESA context of “take” is likely to have significant impacts on species listed as threatened or endangered, the plaintiffs in all four lawsuits argue that the categorical exclusion was misapplied and the Services violated NEPA by failing to prepare an EIS for the Recission Rule.
Going Forward
All four lawsuits are currently in the early stages of litigation, but it is likely that however the cases resolve will have a lasting impact on future implementation of the ESA. If the Recission Rule is ultimately upheld, it would mean that “take” under the ESA would no longer include habitat modification on its own. Instead, only actions that directly kill or injure a member of a protected species will be considered “take.” Because “take” has included habitat modification since 1975, two years after the ESA was enacted, the Recission Rule represents a novel way of understanding and enforcing the ESA. On the other hand, if courts overturn the Recission Rule and determine that the definition of “take” includes habitat modification, it would likely become more difficult for the definition to be modified in the future.
Additionally, the lawsuits may shed light on how courts intend to interpret and apply the Loper Bright standard going forward. The Supreme Court issued Loper Bright v. Raimondo just over two years ago in 2024. However the courts in these lawsuits rule on the arguments involving the Loper Bright standard is likely to inform how agencies and judges view the standard in future cases.
The Recission Rule is currently set to go into effect on September 14, 2026, although it is possible that the rule may be paused by a court before that date. The four federal lawsuits currently challenging the rule have all requested that the rule be enjoined and overturned, and it is possible that further lawsuits may be filed. NALC will continue to provide analysis on this issue as it progresses.
To read the full text of the ESA, click here.
For more resources on the ESA from the National Agricultural Law Center, click here.