Defenders of Wildlife v. Norton

The flat-tailed horned lizard had experienced a reduction in its range due to the development of land, so the United States Fish and Wildlife Service (the service) had been considering the lizard as a candidate for listing under the Endangered Species Act (the act) since 1982. In 1997, in response to a lawsuit from the Defenders of Wildlife (plaintiff), the district court ordered that the secretary of the United States Department of the Interior (defendant) issue a final decision on whether to list the lizard as a threatened species. After the court order, a group of government agencies entered into a conservation agreement to protect the lizard on public lands. The secretary ultimately withdrew the proposed rule that had recommended listing the lizard. The secretary found that there were threats to the lizard on private land but that adequate habitat existed on public land to ensure the survival of the lizard. The secretary reasoned that listing was not required because the lizard was not in danger of extinction as an entire species. The secretary interpreted the act to require listing of a species that faced the threat of extinction throughout a portion of its range only if such a threat would put the species in danger of extinction everywhere. The Defenders of Wildlife sued the secretary, arguing that the secretary’s interpretation of the act was incorrect. The district court granted summary judgment in favor of the secretary. Defenders of Wildlife appealed.