Trump Administration Rescinds the Regulatory Definition of “Harm” Under the Endangered Species Act, Narrowing the Act’s Reach

On July 14, 2026, the US Fish and Wildlife Service and National Marine Fisheries Service (collectively, the “Services”) published a final rule rescinding the definition of “harm” in the Services’ Endangered Species Act (“ESA”) regulations.¹ The ESA prohibits the “take” of endangered species, and defines take as “to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct.”² The Services previously defined harm to include “significant habitat modification or degradation where it actually kills or injures [wildlife] by significantly impairing essential behavioral patterns.”³ The Services’ rescission of this regulatory definition means that significant habitat impacts alone will no longer constitute harm and that more direct impacts will be required to trigger the ESA’s protections.

The Services’ prior definition of harm had not been uncontroversial. In 1995, the US Supreme Court upheld the definition in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon,⁴ applying Chevron⁵ deference to the Service’s interpretation of the statute. In a dissent in that case, Justice Scalia, joined by Chief Justice Rehnquist and Justice Thomas, argued that the expansive definition of harm was inconsistent with the text and structure of the ESA regardless of the Chevron standard. In a quote that the Services cite, Justice Scalia stated that “[i]f ‘take’ were not elsewhere defined in the Act, none could dispute what it means, for the term is as old as the law itself. To ‘take,’ when applied to wild animals, means to reduce those animals, by killing or capturing, to human control.”⁶ Justice Scalia further stated that the definition of harm, like the other nine verbs in the definition of take, should be construed to require an “affirmative act[ ] . . . directed immediately and intentionally against a particular animal.”⁷

The Supreme Court recently overruled the Chevron doctrine in Loper Bright, and in so doing, stated that a statute has a “single, best meaning” that the courts are equipped to determine.⁸ Using the Loper Bright test, the Services concluded that the definition of harm does not match the single, best meaning of the ESA. The Services further concluded that a replacement definition is unnecessary in light of the comprehensive statutory definition of take.

Rescinding the prior regulatory definition of harm narrows the range of activities subject to ESA regulation, but, because the meaning of harm has not been addressed by the Services or the courts without the regulatory definition, the full effect of the Services’ proposal is uncertain, and some habitat impacts would likely still be prohibited. For example, in his dissent in Babbitt, Justice Scalia opined that “to chop down the very tree in which [an animal] is nesting, or even to destroy its entire habitat in order to take it (as by draining a pond to get at a turtle), might neither wound nor kill, but would directly and intentionally harm” the animal and therefore be prohibited by the ESA.⁹ In addition, the Fish and Wildlife Service defines “harass,” another component of the definition of take, as “an intentional or negligent act or omission which creates the likelihood of injury to wildlife by annoying it to such an extent as to significantly disrupt normal behavioral patterns that include, but are not limited to, breeding, feeding, or sheltering.”¹⁰ While such definition could provide another avenue to address habitat impacts, the Services may undertake additional regulatory action to ensure alignment with the rescission of the harm definition.

The Services’ current rule and any subsequent changes to their ESA regulations are likely to be challenged, including, potentially, a call for the Supreme Court to revisit its holding in Sweet Home.

¹ 91 FR 43300.
² 16 U.S.C. 1538(a)(1)(B)-(C), 16 U.S.C. 1532(19).
³ 50 CFR 17.3; 50 CFR 222.102.
⁴ 515 U.S. 687 (1995).
⁵ Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 (1984).
⁶ Babbitt, 515 U.S. at 717.
⁷ Id. at 719-20.
⁸ Loper Bright Enterprises v. Raimondo, 603 U.S. 369, 400 (2024).
⁹ Babbitt, 515 U.S. at 721.
¹⁰ 50 CFR 17.3.

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