The case concerns the delisting of the wolf from the Endangered Species list that occurred in March of 2008. Plaintiffs-Defenders of Wildlife moved for a preliminary injunction, asking the Court to reinstate ESA protections for the wolf. Specifically, plaintiffs argue that even though the Fish & Wildlife Service’s (“Service”) original environmental impact statement (EIS) on wolf reintroduction conditioned the delisting on a finding of genetic exchange between populations, and there is no evidence that such exchange has occurred. Further, the Service approved Wyoming's 2007 wolf management plan even though the Wyoming plan still contains provisions that the Service previously found inadequate. On the whole, the court found that plaintiffs demonstrated a possibility of irreparable harm and granted plaintiff’s Motion for Preliminary Injunction. As a result, the Endangered Species Act protections were reinstated for the northern Rocky Mountain gray wolf pending final resolution of this matter on the merits.

The Humane Society of the United States sought an injunction to prevent the lethal depredation of gray wolves. The district court granted the injunction but, while the case was on appeal, the United States Department of the Interior removed the gray wolf from the Endangered Species List.  After the gray wolf was removed from the Endangered Species List, all parties agreed that the delisting of the gray wolf rendered the appeal moot.  The Court of Appeals vacated the district court's ruling.

The Government issued regulations which allowed for the sport hunting of the Eastern Timber Wolf  (otherwise known as the gray wolf) in Minnesota, where the wolf was listed as threatened.  The court held that such regulations were invalid because the Endangered Species Act, Section 4(d) required that such regulations must be "for the conservation" of the wolf, which means for the best interest of the wolf.  The court found that the hunting of the wolf in this manner did not have the motive of the best interest of the wolf in mind.

The State Farm Bureaus (a national farm organization)), researchers, and environmental groups appealed from decision of United States and federal agencies to introduce experimental population of gray wolves in a national park and central Idaho. The United States District Court for the District of Wyoming struck down the Department of Interior's final wolf introduction rules and ordered reintroduced wolves removed. In reversing the lower court's decision, the Court of Appeals for the 10th Circuit held that the possibility that individual wolves from existing wolf populations could enter experimental population areas did not violate provision of Endangered Species Act requiring that such populations remain "geographically separate."  Further, the fact that the promulgated rules treated all wolves, including naturally occurring wolves, found within designated experimental population areas as nonessential experimental animals did not violate ESA.

The Wyoming Farm Bureau, amateur researchers, and environmental groups appealed an agency to introduce experimental population of gray wolves in a national park and central Idaho. After ruling on the various standing issues, the court held that the ESA section allowing experimental population to be maintained only when it is "wholly separate geographically" from nonexperimental populations includes overlap even with individual members of nonexperimental species.  However, the defendants' treatment of all wolves found within boundaries of designated experimental population areas as nonessential experimental animals was contrary to law as provided in their own regulations.  Therefore, the court ordered that Defendants' Final Rules establishing a nonessential experimental population of gray wolves in Yellowstone National Park in Wyoming, Idaho, Montana, central Idaho and southwestern Montana was unlawful.  Further, that by virtue of the plan being set aside, defendants must remove reintroduced non-native wolves and their offspring from the Yellowstone and central Idaho experimental population areas. This decision was reversed in 199 F.3d 1224.