The U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS; together, the Services) recently rescinded without replacement the definitions of “harm” in regulations pertaining to the Endangered Species Act (ESA). The final rule (Rule) became effective September 14, 2026.

Section 9 of the ESA (16 U.S.C. 1531 et seq.) prohibits the “take” of endangered wildlife. “Take” has a statutory definition of “to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct.” Under Section 10 of the ESA, a non-federal entity undertaking an otherwise lawful project that might result in the take of an endangered species must seek an incidental take permit, which must be accompanied by, among other things, a conservation plan.

Before the recent Rule, FWS’s regulations included a definition of “harm” in the ESA context of “take” that meant “an act which actually kills or injures wildlife. Such an 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). NMFS’s regulations included a similar definition for “harm” that meant “an act which actually kills or injures fish or wildlife. Such an act may include 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.” (50 C.F.R. § 222.102).

Relying heavily on a dissent authored by Justice Antonin Scalia in a 1995 Supreme Court case, Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, 515 U.S. 687 (1995) (Sweet Home), the Services found that the regulatory definitions of “harm” were “unlawful” and that they transformed Sections 9 and 10 of the ESA into “sweeping” land use regimes. The Services determined that the regulatory “harm” definitions would not be replaced and that the plain text of the statute governs.

An internal FWS memo dated September 14, 2026, indicates that the Rule not only rescinded the “harm” definitions but also “adopted Justice Scalia’s interpretation of ‘take’ set out in the dissent in [Sweet Home].” The memo specifies that this interpretation of “take” reaches only “an affirmative act that is intentionally and purposefully directed at a particular animal” without any “intervening link.”

Section 7 of the ESA still requires certain consultations with the Services to ensure that actions authorized, funded, or carried out by federal agencies are not likely to “jeopardize the continued existence of any endangered species or threatened species or result in the destruction or adverse modification of habitat of such species which is determined by the Secretary, after consultation as appropriate with affected States, to be critical. . . .”

The Services’ responses to comments indicate that they will maintain this consultation obligation as a separate responsibility under the law and acknowledge that “not only is the statutory prohibition in section 7 against habitat modification not affected at all by the deletion of the definition of ‘harm’ . . . , but the presence of this separate and distinct provision in the statutory text regarding habitat modification reinforces the Services’ conclusion that habitat modification is not properly part of the definition of “take,” as such a construction would violate the canon against surplusage.” At the same time, the Services stated that they do not view the consultation obligation as “continu[ing] to subject a swatch of activities to the incidental-take regime”.

The Rule—which is part of a package of ESA rollbacks by the Trump administration—is the subject of multiple litigations, including an action brought by 21 state attorneys general. Other recent rulemakings have removed broad protections for newly listed threatened species and subjected critical habitat designations to a balancing test involving economic impact, national security, and “any other relevant impact.” In March 2026, the Endangered Species Committee voted unanimously to exempt oil and gas drilling activity in the Gulf of Mexico from ESA restrictions—also subject to numerous litigations.

These recent changes have implications for developers with projects both with and without a federal nexus. For private activities with no federal nexus, habitat modification may no longer require incidental take permits; for those with a federal nexus, consultations and incidental take permits may still be required but possibly with significantly narrowed scopes. These changes, of course, do not alter obligations under state or local law, and citizen suits and other actions by private parties remain a risk. Given the unsettled nature of these changes, developers should tread carefully.