Amid ongoing political shifts and court challenges over the last several years, different administrations have promulgated multiple revisions to the Endangered Species Act’s (ESA) core implementing regulations governing ESA species listing, critical habitat designations, take protections for threatened species and interagency consultation. On November 21, 2025, the Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) (collectively the Services) continued this trend, and published four proposed rules in the Federal Register (collectively the 2025 Proposal) proposing once again to revise the ESA’s implementing regulations governing: (1) Section 7 interagency consultation; (2) Section 4(d) rules applicable to the take of threatened species; (3)Section 4 listing of species as endangered or threatened and critical habitat designation; (4) Section 4(b)(2) exclusions from critical habitat designations.
Public comments on the 2025 Proposal must be submitted by December 22, 2025.
Key Proposed Revisions
Until relatively recently, the Services regulations implementing the listing, critical habitat, and consultation programs had remained largely unchanged since the 1980s. This changed in 2019 when the first Trump administration issued significant revisions to the ESA regulations governing the procedures and standards for implementing ESA sections 4, 4(d), and 7 (the 2019 Trump I Regulations). After legal challenges that resulted in a remand without vacatur, the Biden administration issued new regulations in 2024 (the 2024 Biden Regulations). These 2024 revisions altered some, but not all, of the changes adopted in the 2019 Trump I Regulations. Below highlights some of the most prominent changes contained in the 2025 Proposal.
ESA Section 7 Interagency Consultation
- Reasonable and Prudent Measures (RPMs). The 2024 Biden Regulations added provisions that allow the Services to include measures (RPMs) in the Incidental Take Statement accompanying a Biological Opinion to require the agency or project applicant to offset or compensate for the impacts of an incidental take of a listed species. These provisions had not been in any of the previous regulations. The 2025 Proposal would rescind these provisions entirely and revert to the 2019 Trump I Regulations’ approach, which limits reasonable and prudent measures to minimize the amount or extent of an incidental take, do not alter the basic design, location, scope, duration or timing of the action, and may involve only minor changes.
- Environmental Baseline. While the 2024 Biden Regulations made only relatively minor revisions to the 2019 Trump I Regulations’ definition of “environmental baseline.” The 2025 Proposal would revert to the 2019 Trump I Regulations’ definition and add some modest clarifying language. At bottom, the proposed revision would retain and reinforce that the environmental baseline should be used to compare the condition of the listed species and the designated critical habitat in the action area with and without the effects of the proposed action, and that non-discretionary components of federal activities or federal facilities are considered part of the baseline, not part of the proposed action subject to consultation.
- Effects of the Action. The 2019 Trump I Regulations defined “effects of the action” — which establishes the scope of analysis for determining whether a federal agency action is likely to jeopardize listed species or adversely modify critical habitat — as consequences to listed species or critical habitat that are “caused by the proposed action,” including the consequences of other activities that are caused by the proposed action. A consequence is caused by the proposed action “if it would not occur but for the proposed action and it is reasonably certain to occur.” The 2019 Trump I Regulations also provided further granularity as to what constitutes “reasonably certain to occur” and “caused by the proposed action,” limiting the scope of “effects of the action.” The 2024 Biden Regulations maintained the definition of “effects of the action,” but rescinded the 2019 Trump I Regulations’ articulation of “reasonably certain to occur” and “caused by the proposed action.”
The 2025 Proposal: (1) would maintain the 2019 Trump I regulations definition of “effects of the action,” and (2) would restore with added detail, what constitutes “reasonably certain to occur” and “caused by the proposed action,” stating that the assessment is to be based on “clear and substantial information.” The 2025 Proposal would reinstate factors included in the 2019 Trump I regulations to be considered in this assessment such as: (a) whether the consequence is remote in time or geography from the action, and (b) whether the connection between the action and consequence would involve a lengthy causal chain that involves so many steps as to make the consequence not reasonably certain to occur. The 2025 Proposal would also add two new factors: (c) whether the agency has the ability to prevent the consequence due to its limited statutory authority, and (d) whether the consequence would occur regardless of whether the proposed action goes forward. Notably, the 2025 Proposal specifically references the Supreme Court’s Seven County Infrastructure NEPA decision as support, indicating an attempt to import a similar causation standard into the ESA’s assessment of effects of the action.
ESA Section 4(d) Applicability of the “Take” Prohibition to Threatened Species
ESA section 9 prohibits the unauthorized “take” of species listed as endangered under the ESA.Although section 9’s prohibition on an unauthorized “take” does not extend to species listed as threatened, ESA section 4(d) authorizes the Services to issue protective regulations that they deem “necessary and advisable” to provide for the conservation of threatened species. Such regulations can include prohibitions on the “take” of threatened species. Historically, FWS relied on a “blanket” 4(d) regulation that presumptively prohibits the “take” of a newly listed threatened species unless otherwise specified. Conversely, NMFS did not rely on a “blanket” 4(d) regulation, meaning that presumptively, there was no prohibition on the “take” of a newly listed threatened species unless otherwise specified.
The 2019 Trump I Regulations rescinded the FWS “blanket” 4(d) rule and instead provided that FWS would issue species-specific take rules for threatened species upon listing consistent with NMFS’ practice. The 2024 Biden Regulations re-imposed the FWS’ “blanket” 4(d) rule for threatened species. The 2025 Proposal would rescind the Biden “blanket” 4(d) rule and again require FWS to issue species-specific take rules for threatened species upon listing consistent with NMFS’ practice. This proposed rule relates only to the FWS regulations.
ESA Section 4 Listing and Critical Habitat Designation
- Definition of Foreseeable Future. The ESA defines a “threatened species” as any species which is likely to “become an endangered species within the foreseeable future throughout all or a significant portion of its range.” The Act does not further define the term “foreseeable future.” The 2025 Proposal would reinstate the 2019 Trump I Regulations definition of “foreseeable future,” which extends only so far into the future as the Services can reasonably determine that both the future threats and the species’ responses to those threats are likely.This proposed change, however, is relatively modest as the 2019 Trump I Regulations’ and 2024 Biden Regulations’ definitions largely tracked each other. The proposed revision is intended to tighten and clarify the language.
- Designation of Unoccupied Areas as Critical Habitat. The ESA directs the Services to designate critical habitat for listed species to the maximum extent prudent and determinable. The Act defines critical habitat to include both areas currently occupied by the species and areas not currently occupied by the species but that are essential for the species conservation (i.e., “unoccupied habitat”). The 2019 Trump I Regulations revised the criteria for designating unoccupied critical habitat to explicitly require a two-step process that prioritizes the designation of occupied areas over unoccupied areas (i.e., the Services would consider designating unoccupied areas as critical habitat only if designating just the occupied habitat would be inadequate for conservation of the species). The 2024 Biden Regulations revised the critical habitat designation process to allow simultaneous consideration of occupied and unoccupied habitat, rather than first considering if designation of occupied areas was sufficient for conservation of the species. The 2025 Proposal would revert to the 2019 Trump I Regulations’ formulation and again requires a stepwise approach to designating critical habitat.
- Definition of Not Prudent. The ESA requires designation of critical habitat to the “maximum extent prudent and determinable.” The 2025 Proposal would expand the bases upon which the Services could conclude that designation of critical habitat for a species would not be prudent.
ESA Section 4(b)(2) Exclusions to Critical Habitat Designation
ESA section 4(b)(2) directs the Services to designate critical habitat on the basis of the “best scientific data available and after taking into consideration the economic impact, the impact on national security, and any other relevant impact, of specifying any particular area as critical habitat.” The Act also provides that Services may exclude any area from critical habitat if the Secretary of the Interior or Commerce determines that the benefits of such exclusion outweigh the benefits of designating such area as part of the critical habitat, unless the relevant Secretary determines that the failure to designate such area as critical habitat will result in the extinction of the species concerned.
The 2025 Proposal would expand on the framework FWS uses to evaluate exclusions. In particular, it would expand the scope of costs to be considered, reverses the presumption that Federal lands generally are not subject to exclusion, and increases the possibility that voluntary conservation agreements or plans (including non-final plans) can be a basis for exclusion. Thus, the 2025 Proposal aims to expand the bases for excluding areas from the designation of critical habitat.
Takeaways
The 2025 Proposals would largely revert the provisions that the Biden administration changed in 2024 back to the 2019 Trump I Regulations and in that sense, they are not as dramatic as they might have been. Nonetheless, as with past proposed ESA regulatory changes, these proposed revisions are likely to engender a substantial number of public comments. In addition, any final regulations arising from the 2025 Proposal are likely to face judicial challenges.
Public comments on the 2025 Proposals are due on December 22, 2025. Bracewell will continue to monitor developments regarding ESA.
If you have any questions, please reach out to Bracewell’s environment, lands and resources team.
