
Rescinding the Definition of “Harm” Under the ESA: A Turning Point for Habitat-Based Protection?
Bethany C. Aragon
Published July 29, 2025
6 Minute Read
On April 17, 2025, the U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS)—the two Services that share responsibility for administering the Endangered Species Act (ESA)1—jointly proposed rescinding the ESA’s long-established regulatory definition of “harm.”2 The agencies characterized the proposal as a technical clarification, and it reflects recent priorities issued by the Trump administration. While framed as a technical clarification, the proposal could bring significant changes to how habitat impacts are regulated under the ESA—changes that will require clarity to ensure compliance by all affected stakeholders.
I. Background: The ESA and the Definition of “Harm”
The ESA prohibits any person from “taking” an endangered species,3 and the act defines “take” to mean “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct.”4 In implementing regulations, the two Services further defined “harm” to mean “an act which actually kills or injures wildlife,” incorporating acts that “may include significant habitat modification or degradation.”5
In 1995, the U.S. Supreme Court upheld the Services’ regulatory definition of “harm” in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon. Citing Chevron U.S.A. Inc. v. NRDC, 467 U.S. 837 (1984), the Court deferred to the Fish and Wildlife Service’s interpretation and held that habitat alteration that causes actual injury or death to wildlife may constitute “harm.”6 The decision, however, was not unanimous. Chief Justice Rehnquist and Justice Thomas joined Justice Scalia’s dissent, which argued that including habitat modification within the definition of “harm” extended the ESA beyond its original intent.7
II. The Proposed Rescission and Service Justification
The proposed rule rescinds the regulatory definition of “harm” from 50 C.F.R. § 17 and § 222—the implementing regulations of FWS and NMFS, respectively. The Services assert that “the ESA itself defines ‘take,’” and that further elaboration on just one component—“harm”—is unnecessary.8 They claim the rescission will reduce confusion and better align with the “plain language, structure, and purposes of the ESA.”9
In justifying the rescission, the Services draw heavily from Justice Scalia’s dissent in Babbitt v. Sweet Home, which argued that the regulatory definition of “harm” was not sustainable even under Chevron. Scalia viewed the definition as unnecessary, since “take” was already clearly defined, and emphasized that isolating “harm” for additional definition—inconsistent with the other nine verbs in the “take” definition—violated the noscitur a sociis canon.10
Importantly, the Services emphasize that rescinding the regulatory definition does not alter the statutory definition of “take,” nor does it prevent enforcement against habitat-based harms when they result in the death or injury of a listed species.11
III. Legal and Political Context: Why This Matters Now
The proposed rescission is one of several environmentally related regulatory changes being advanced under President Trump’s February 19, 2025 Executive Order, Ensuring Lawful Governance and Implementing the President’s “Department of Government Efficiency” Deregulatory Initiative,12 and an April 9, 2025 Presidential Memorandum, Directing the Repeal of Unlawful Regulations.13 The President directed agency and department heads to conduct a 60-day “review and repeal” process to identify regulations that may be unlawful or inconsistent with a list of recent U.S. Supreme Court decisions.14
The first case on that list was the Supreme Court’s 2024 decision in Loper Bright Enterprises v. Raimondo, which overruled the longstanding Chevron doctrine.15 Writing for the majority, Chief Justice Roberts concluded that Chevron’s framework—under which courts deferred to agency interpretations of ambiguous statutes—conflicted with the judiciary’s constitutional role of interpreting the law.16 With Chevron overturned, courts now apply their own independent judgment in determining whether agency regulations are consistent with statutory authority.
Given the 60-day “review and repeal” directive, the Loper Bright decision, and the longstanding controversy over the regulatory definition of “harm” addressed in Babbitt v. Sweet Home, it is not surprising that FWS and NMFS selected this rule for repeal under the administration’s initiative.
IV. Stakeholder Reactions and Legal Implications
The comment period closed on May 19, 2025 and the proposed rescission drew more than 242,000 public comments in just 30 days—a high volume for technical rulemaking.17 Although its per-day comment rate was lower than the 2020 National Environmental Policy Act (NEPA) regulatory overhaul (which received more than 720,000 comments over 60 days),18 the intensity of response still reflects the importance and controversy of habitat-based protections under the ESA. By late June, the comment count had climbed to over 357,000, underscoring continued public engagement.19
The proposed rule has elicited divergent responses from stakeholders:
- Leading national environmental organizations—including the Animal Legal Defense Fund, PETA, the Natural Resources Defense Council, and Defenders of Wildlife— oppose the rescission, arguing that it undermines the ESA’s core function of protecting endangered species by weakening enforcement against habitat destruction.20
- Sixteen state attorneys general, led by California, submitted comments urging the Services to retain the current definition, emphasizing the importance of clarity and consistency in ESA enforcement.21
- Industry groups such as the National Association of Home Builders support rescission, arguing that the current definition of “harm” contributes to permitting delays, legal uncertainty, and burdensome compliance obligations for landowners and developers. They also emphasize the need for clear guidance on how to interpret the term moving forward, so that affected parties can understand their obligations and avoid noncompliance.22
- The U.S. Small Business Administration and other business coalitions formally submitted comments supporting rescission, asserting that the current habitat‑based definition of “harm” creates regulatory ambiguity, litigation risk, and economic burdens for small businesses and local governments.23
V. Implications for the West—and for Wyoming
Western states like Wyoming are home to both iconic wildlife and working landscapes. The Wyoming Game and Fish Department supported rescission, citing the need for clearer, more tailored regulation that respects state expertise and reduces unnecessary litigation.24 Similarly, the Klamath Irrigation District welcomed the change as a step toward limiting federal overreach into land and water use.25
At the same time, wildlife-based tourism, hunting, and fishing are cornerstones of Western identity and economy. Removing the regulatory definition of “harm” could limit federal tools for preventing habitat-related takings, particularly on private lands. As states continue balancing conservation with landowner rights and resource use, the West will remain a key proving ground for how the ESA evolves post-Chevron.
VI. Conclusion
The proposed rescission of the regulatory definition of “harm” marks a significant moment in the evolution of the ESA. While the agencies present it as a technical clarification, its timing and context suggest broader legal and political stakes. In a post-Chevron world, regulatory clarity may matter more than ever—and how “harm” is defined could determine whether habitat-based protections remain a cornerstone of endangered species conservation or are left to the states to regulate.
Footnotes
- 50 C.F.R. § 402.01 (Lexis Advance through the June 23, 2025 issue of the Federal Register, excluding amendments appearing at 90 Fed. Reg. 26,455).
- 90 Fed. Reg. 16,102 (Apr. 17, 2025), available at https://www.federalregister.gov/d/2025-06746.
- Endangered Species Act of 1973, 16 U.S.C. § 1538(a)(1) (LexisNexis, Lexis Advance through Pub. L. No. 119-20, approved June 20, 2025).
- 16 U.S.C.S. § 1532(19) (Lexis Advance through Pub. L. No. 119-20, approved June 20, 2025).
- 50 C.F.R. §17.3 https://www.ecfr.gov/current/title-50/part-17/section-17.3.
- Babbitt v. Sweet Home Chapter of Cmtys. for a Great Or., 515 U.S. 687, 708 (1995).
- Id. at 735-36.
- 90 Fed. Reg. 16,102 (Apr. 17, 2025), available at https://www.federalregister.gov/d/2025-06746.
- Id.
- Id.
- Id.
- Exec. Order No. 14,219, Ensuring Lawful Governance and Implementing the President’s “Department of Government Efficiency” Deregulatory Initiative, 90 Fed. Reg. 10,583, (Feb. 25, 2025), https://www.federalregister.gov/d/2025-03138.
- Presidential Memorandum, Directing the Repeal of Unlawful Regulations (Apr. 9, 2025), https://www.whitehouse.gov/presidential-actions/2025/04/directing-the-repeal-of-unlawful-regulations/.
- Id.
- Loper Bright Enters. v. Raimondo, 603 U.S. 369 (2024).
- Id. at 412.
- Rescinding the Definition of “Harm” Under the Endangered Species Act, Docket No. FWS–HQ–ES–2025–0034, https://www.regulations.gov/document/FWS-HQ-ES-2025-0034-0001/comment
- Update to the Regulations Implementing the Procedural Provisions of the National Environmental Policy Act, Docket No. CEQ-2019-0003-0001, https://www.regulations.gov/document/CEQ-2019-0003-0001/comment
- Rescinding the Definition of “Harm” Under the Endangered Species Act, Docket No. FWS–HQ–ES–2025–0034, https://www.regulations.gov/document/FWS-HQ-ES-2025-0034-0001/comment
- Animal Legal Defense Fund et al., Comment on Proposed Rule to Rescind Definition of “Harm,” Docket No. FWS–HQ–ES–2025–0034 (May 19, 2025), https://www.regulations.gov/document/FWS-HQ-ES-2025-0034-0001/comment; Natural Resources Defense Council, Comment on Proposed Rule to Rescind Definition of “Harm,” Docket No. FWS–HQ–ES–2025–0034 (May 27, 2025), https://www.regulations.gov/comment/FWS-HQ-ES-2025-0034-242737; Defenders of Wildlife, Comment on Proposed Rule to Rescind Definition of “Harm,” Docket No. FWS-HQ-ES-2025-0034 (May 19, 2025), https://www.regulations.gov/comment/FWS-HQ-ES-2025-0034-223181.
- State of California et al., Multi-State Comment on Proposed Rule to Rescind Definition of “Harm,” Docket No. FWS–HQ–ES–2025–0034 (May 19, 2025), https://www.regulations.gov/document/FWS-HQ-ES-2025-0034-0001/comment.
- National Association of Homebuilders, Comment on Proposed Rule to Rescind Definition of “Harm,” Docket No. FWS–HQ–ES–2025–0034 (May 19, 2025), https://www.regulations.gov/comment/FWS-HQ-ES-2025-0034-223165.
- U.S. Small Business Administration, Comment on Proposed Rule to Rescind Definition of “Harm,” FWS-HQ-ES-2025-0034 (May 19, 2025), https://www.regulations.gov/comment/FWS-HQ-ES-2025-0034-223160.
- Wyoming Game and Fish Dep’t, Comment on Proposed Rule to Rescind Definition of “Harm,” FWS-HQ-ES-2025-0034 (May 19, 2025), https://www.regulations.gov/document/FWS-HQ-ES-2025-0034-0001/comment.
- Klamath Irrigation District, Comment on Proposed Rule to Rescind Definition of “Harm,” Docket No. FWS–HQ–ES–2025–0034 (May 1, 2025), https://www.regulations.gov/comment/FWS-HQ-ES-2025-0034-69781.
Photo credit: US Forest Service, Rocky Mountain Research Station