Humane Society of the United States v. Zinke

In 1973 Congress passed the Endangered Species Act (the act), under which the Department of the Interior (the department) could deem a species or subspecies endangered. The term subspecies was defined as a distinct population segment that interbreeds. The department issued a policy requiring that a subspecies be significant, meaning the species would be in danger of extinction by losing the subspecies. The act required the department to consider certain factors to deem a species endangered, including the destruction of the species’ habitat or range. The department promulgated a rule defining range as the species’ current range rather than its historical range. This allowed the department to consider whether a subspecies was endangered based on a threat to its current habitat. In 2011 the department tried withdrawing from the endangered list a subspecies of gray wolves called the Western Great Lakes gray wolf population. The department based its decision on the fact that the subspecies’ current range, i.e., the Western Great Lakes, was not in danger of destruction. The Humane Society of the United States (the society) (plaintiff) sued the Secretary of Interior Ryan Zinke (defendant). The society argued that the new rule withdrawing the Western Great Lakes gray wolves from the endangered-species list was arbitrary and capricious because the department had not considered the subspecies’ impact on the entire gray wolf population. The district court returned a verdict for the society. The matter was appealed.