## Facts

- The U.S. Fish and Wildlife Service (FWS) listed the Northern Rocky Mountain (NRM) gray wolf as endangered and later pursued delisting based on recovery planning that included numeric targets and, in later iterations, genetic exchange among three core recovery areas (Greater Yellowstone, central Idaho, and northwestern Montana).
- FWS issued a 2008 rule designating the NRM gray wolf as a distinct population segment (DPS) and delisting that DPS across Montana, Idaho, and Wyoming, relying heavily on state management plans.
- Plaintiffs (conservation organizations) asserted that prior agency documents conditioned delisting on a “Finding of Subpopulation Genetic Exchange,” yet the administrative record lacked a plausible showing of required genetic exchange between core areas.
- Plaintiffs also challenged FWS’s acceptance of Wyoming’s regulatory framework, which treated wolves as predators in much of the state, allowed broad lethal take under “defense of property” provisions, and did not clearly commit to minimum wolf population levels.
- Plaintiffs sought a preliminary injunction to restore ESA protections during litigation, arguing that delisting would increase human-caused mortality and cause irreversible losses to wolves and to plaintiffs’ conservation, recreational, and aesthetic interests.

## Issues

1. Whether plaintiffs showed a likelihood of success on the merits that the 2008 DPS designation and delisting rule violated the ESA and was arbitrary and capricious under the APA, including by departing from prior recovery criteria regarding genetic connectivity and by unreasonably approving Wyoming’s regulatory mechanisms.
2. Whether plaintiffs showed likely irreparable harm absent an injunction, and whether the balance of equities and public interest favored interim relief restoring ESA protections.

## Decision

- The court granted plaintiffs’ motion for a preliminary injunction.
- The court found plaintiffs demonstrated a substantial likelihood of success on the merits of their ESA/APA claims.
- The court found a likelihood of irreparable harm because increased lethal take under state regimes would cause irreversible loss of wolves and could impair the population’s viability during litigation.
- The court held the balance of harms and the public interest favored maintaining ESA protections pending review of the rule’s legality.
- The injunction reinstated federal ESA protections for the NRM gray wolf DPS while the case proceeded.

## Legal Principles

- Under the APA, an agency’s unexplained departure from prior policy, criteria, or factual premises is vulnerable as arbitrary and capricious; the agency must provide a reasoned explanation for a material change in approach.
- Under ESA § 4, delisting must be supported by a reasoned determination that the species is not endangered or threatened, including consideration of the adequacy of “existing regulatory mechanisms.”
- A state management plan’s permissive lethal-take rules and weak commitments to minimum population levels can undermine the adequacy of regulatory mechanisms supporting delisting.
- In ESA cases, likely unlawful agency action coupled with irreversible wildlife mortality can satisfy preliminary-injunction requirements, with species-protection considerations weighing strongly in the public-interest analysis.

## Conclusion

The court enjoined implementation of the 2008 NRM gray wolf delisting rule, concluding that plaintiffs were likely to prove the rule unlawful under the ESA and APA and that delisting posed a substantial risk of irreversible harm; ESA protections were restored pending final resolution on the merits.


Defenders of Wildlife v. Hall, 565 F. Supp. 2d 1160 (D. Mont. 2008)