The Endangered Species Act of 1973 (ESA) makes it unlawful for any person to “take” endangered species[1] and defines “take” to mean to “harass, harm, pursue,” “wound,” or “kill.”[2] In implementing regulations, the Fish and Wildlife Service and the National Marine Fisheries Service (“the Services”) have for over 40 years defined “harm” to include “significant habitat modification or degradation where it actually kills or injures wildlife.”[3] The Services used a broader regulatory definition of “harm” prior to 1981.[4] Habitat loss is a major threat to species across the United States.
On April 17, 2025, the Services proposed rescinding the longstanding definition of “harm” under Section 9 of the Endangered Species Act. The Services explained in the proposal that the definition of “harm,” which currently includes habitat loss and modification, “runs contrary to the best meaning” of the statute.
In a 1995 opinion written by Justice Stevens and joined by Justices O’Connor, Kennedy, Souter, Ginsberg, and Breyer, Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, the Court held that “significant habitat modification or degradation that actually kills or injures wildlife” could reasonably be considered part of “harm” to species under the ESA.[5] This decision relied in part on Chevron Step 2 to bypass the underlying question of whether “take” as defined in the statute could include this regulatory definition of “harm.” The Court explained that the statutory definition of “take” (which includes “harm”) was ambiguous and the way the Fish and Wildlife Service defined “harm” in regulation was reasonable for a variety of reasons, allowing the Court to apply Chevron deference.
Now, the Trump administration uses Justice Scalia’s dissent in Sweet Home to conclude that the current regulations “do not match the single, best meaning of the statute,” arguing that “the regulations’ interpretation of the statutory language violates the noscitur a sociis canon [suggesting that a word is defined in context of surrounding words], did not properly account for over a thousand years of history, and is inconsistent with the structure of the ESA.” The Services states that no replacement definition is needed, as the statute already defines “take” and further explanation of the term “harm” “is unnecessary in light of the comprehensive statutory definition.”
The Services acknowledge that the 2024 Loper Bright Enterprises v. Raimondo decision[6] overturning Chevron did not call into question cases previously decided under the Chevron framework. Nonetheless, they explain that rescinding the definition “on the ground that it does not reflect the best reading of the statutory text . . . would not only effectuate the Executive Branch’s obligation to ‘take Care that the Laws be faithfully executed,’ but would also be fully consistent with Sweet Home.”
In the proposal, the Services request public comment on whether there are “legitimate reliance interests” on the current regulations, noting possible environmental, aesthetic, and property rights interests, but stating that “we believe that reliance interests likely will be outweighed by the constitutional interest in repealing regulations that do not reflect the best reading of the statute.” The Services also invite the public to comment on whether and how NEPA analysis should apply. Comments are due by May 19.
This proposed rollback is one step in the Trump administration’s aggressive deregulatory agenda, laid out in a series of executive orders. The administration signaled in an April memorandum and fact sheet that it plans to use the Loper Bright decision to justify rolling back rules that it believes are not grounded in the “best meaning” of a statute. This proposed rule uses the pretext of Loper Bright to justify a rescission despite the fact that Loper Bright is not intended to unsettle past caselaw decided using the Chevron framework. Loper Bright applies to legal interpretations by courts, expressly limiting agencies’ authority to interpret the law.
The proposal ignores abundant scientific evidence that habitat loss harms threatened and endangered species, but it does not come as a surprise. Rolling back this definition has long been a priority for some organizations and was expected after Loper Bright.
We will be watching how the Services respond to commenters in the final rule, how courts view the Services’ justification in the final rule, and the practical impact of the final rule on habitat protection.
[1] 16 U.S.C. § 1538.
[2] 16 U.S.C. § 1532.
[3] “Harm in the definition of ‘take’ in the Act means an act which actually kills or injures wildlife. Such act may 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; 50 C.F.R. § 222.102.
[4] As the Services explain, the earlier regulatory definition could have been read to include habitat modification or degradation without evidence of death or injury to species 46 FR 54748-01.
[5] Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, 515 U.S. 687 (1995).
[6] Loper Bright Enterprises v. Raimondo, 603 U.S. 369, 394 (2024).