Depts. of Interior and Commerce proposed rescinding regulatory definition of 'harm' under Endangered Species Act, and relying solely on statute’s narrower 'take' definition; if finalized, change would reverse 50 years of policy

On April 17, 2025 , the Departments of Interior and Commerce issued a proposed rule to rescind the regulatory definition of "harm" under the Endangered Species Act (ESA) which, if finalized, would fundamentally alter a significant, long-established element of ESA interpretation and enforcement. The proposed rule is open for public comment here through May 19, 2025 .

The core purpose of the ESA is to prohibit the "take" of endangered species. Thereunder, "[t]he term 'take' means to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct." Regulations previously promulgated by the U.S. Fish & Wildlife Service (FWS) and other federal agencies expanded the ESA's reach in ways, according to the current Administration, "that do not reflect the best reading of the statute."

More specifically, for decades federal regulations have interpreted "harm" to encompass not only direct actions like hunting and trapping, but also "significant habitat modification or degradation which actually kills or injures fish or wildlife by significantly impairing essential behavioral patterns, including breeding, spawning, rearing, migrating, feeding or sheltering." This interpretation has been a major element of species protection, predicated on the notion that the destruction of habitat can be just as harmful as direct actions against listed species.

In 1995, the U.S. Supreme Court upheld the current definition of "harm" in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, conferring "Chevron deference" to the Department of Interior's interpretation of the ESA . The Court held that interpreting "harm" to include habitat modification was a reasonable reading of the ESA in light of its purpose to provide broad protection for endangered species.

However, the newly proposed rule notes the Chevron doctrine was overruled last year in Loper Bright Enterprises v. Raimondo and, that under Loper, "the question that matters" is whether "the statute authorizes the challenged agency action." In other words, according to FWS, "does the agency's regulation match the single, best meaning of the statute?" The proponent agencies now contend that existing regulations, which still contain the definition of "harm" contested in Babbitt,"do not match the single, best meaning of the statute." As such, they propose to rescind the regulatory definition of "harm" and stand on the more narrow statutory definition of "take." Notably, this revision would be prospective only and would not affect permits that have been granted as of the effective date of the new regulation, if finalized.

On the other hand, if adopted, this proposed rule would unquestionably result in a marked departure from 50 years of established ESA enforcement policy. Industry and property rights advocates have long sought this change based on their views that the current definition of "harm" is overbroad and unduly burdensome. Conversely, environmental advocates believe any such change could have devastating consequences on habitat protection. Finally, it is important to note that the proposed rule would not affect state-level protections for endangered species habitats, including in California .

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