On July 14, 2026, the U.S. Fish and Wildlife Service (“FWS”) and National Marine Fisheries Service (“NMFS”) (collectively, the “Services”) jointly finalized a rule rescinding the regulatory definition of “harm” under the federal Endangered Species Act (“ESA”). The final rule will take effect 60 days after publication and represents the culmination of the Services’ April 17, 2025 rulemaking proposal to remove the definition.
The action marks a substantial shift in the Services’ interpretation of the ESA’s prohibition on “take” by rescinding a broad regulatory definition of “harm” that has been in place for decades and has long been interpreted to encompass certain forms of habitat modification that result in injury or death to ESA-listed species.
Background
Section 9 of the ESA prohibits the “take” of listed wildlife species by private citizens and entities. The statute defines “take” to mean “to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct.” Section 10 of the ESA authorizes the Services to issue incidental take permits for otherwise lawful activities that may result in the incidental take of listed species, subject to permit conditions and conservation planning requirements.
For decades, the Services’ regulations have defined “harm” to include “significant habitat modification or degradation where it actually kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding or sheltering.” 50 C.F.R. § 17.3. That regulatory definition was upheld in 1995 by the U.S. Supreme Court in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon (“Sweet Home”). 515 U.S. 687 (1995). However, in a dissent joined by two other judges, Justice Scalia argued that the term “harm” should be limited to “affirmative acts . . . directed immediately and intentionally against a particular animal—not acts or omissions that indirectly and accidentally cause injury to a population of animals,” such as habitat modification that impairs breeding patterns. Id. at 720–21.
In the 2025 proposal, FWS and NMFS concluded that the regulatory definition did not reflect the best interpretation of the ESA’s text and structure. In the final rule, the Services reiterate that view and expressly rely on the reasoning set forth in Justice Scalia’s Sweet Home dissent.
What the Final Rule Does
The final rule removes the regulatory definition of “harm” from the Services’ ESA implementing regulations. The Services determined that no replacement definition is necessary, concluding that the existing text and structure of the ESA support a narrower understanding of “take” that does not extend to habitat modification alone. In support of that conclusion, the Services expressly adopt Justice Scalia’s dissent in Sweet Home.
Accordingly, the Services state that ESA implementation will return to the statute’s text, without a separate regulatory definition of “harm.” The Services explain that the rescission is intended to align ESA implementation with what they view as the best reading of the statute. In interpreting and applying the term “harm” moving forward, the Services maintain they will review each specific situation and species’ response to a proposed action to determine whether it constitutes “harm,” noting that the term should be construed to require an “affirmative act” directed “immediately and intentionally against a particular animal” in alignment with Justice Scalia’s dissent in Sweet Home.
The Services emphasize that the rule change is prospective and does not require reevaluating existing permits and incidental take statements finalized prior to the rule’s effective date. However, the Services explain that future incidental take permit applicants will no longer be required to address habitat modification and degradation in the manner previously required under the rescinded definition of “harm.”
What to Watch Next
Although the rule is now finalized, its practical implications will likely continue to develop through agency implementation and litigation challenging the rule, including two lawsuits already filed by environmental groups.
For now, regulated entities should be aware that the Services have formally withdrawn the regulatory definition of “harm” that has been part of the ESA framework for decades. At the same time, the Services emphasize that other ESA provisions—including those governing critical habitat designation and federal agency Section 7 consultations—remain unchanged.
We will continue to monitor developments, including any legal challenges to the rule and future agency guidance regarding its implementation. Regulated entities with questions about the rule or its potential implications for ongoing or planned projects should contact a member of our Environmental, Land Use & Natural Resources team for additional information and project-specific guidance.