The 1973 Endangered Species Act has been described by the United States Supreme Court as "the most comprehensive legislation for the preservation of endangered species ever enacted by any nation."
A plant or animal listed as "endangered" is considered to be "in danger of extinction throughout all or a significant portion of its range." Those listed as "threatened" (like the northern spotted owl) are thought likely to become endangered in the near future. The law defines "species" to include sub-species or (for vertebrates) specific populations.
About 50 species are added to the list every year, which now totals about 1,200 in the US. Only about one-third of those have recovery plans in place, however, and 37 percent of listed species continue to decline in number. About 4,000 species are considered candidates for possible listing.
Listed species may not be "taken," which means to "harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or collect, or to attempt to engage" in such conduct. Economic considerations may not be taken into account in listing species, but they may in the designation of "critical habitat" or in the formulating of recovery plans.
The act also provides for an Endangered Species Committee (dubbed the "God Squad" because of its life-or-death decisionmaking power) to review listings and grant exemptions based on economic factors. The group is made up of the secretaries of Agriculture, the Army, and the Interior; the chairman of the Council of Economic Advisers; the administrator of the EPA, the administrator of the National Oceanic and Atmospheric Administration, and one gubernatorial-appointee from each affected state. It takes five
of the seven to pass an exemption.