The Endangered Species Act of 1973 was one of dozens of environmental laws passed in the 1970s in the United States. It is designed to protect biodiversity from "the consequences of economic growth and development untempered by adequate concern and conservation."
The Fish and Wildlife Service is responsible for implementing the Act. When a plant or animal species is identified as "threatened" or "endangered" it is put onto a list. (Endangered species are closer to extinction than threatened species.)
It is illegal to kill, buy, sell or trade listed species. The penalties for violating the Endangered Species Act can be as serious as a $50,000 fine and up to a year in jail.
Further, the FWS develops a plan to help the listed species recover. Some species, such as the American Bald Eagle have successfully made it off the list. Others have become extinct.
The Act provides a citizen enforcement clause. This allows anyone to sue the FWS to list a species with dwindling numbers or to force enforcement of the law or an existing plan.
This law has created controversy when the Congress attempted to limit the number of species which can be limited. Also, some people argue that when a plan restricts the use of private property it is equivalent to a "taking" or an illegal use of the government's eminent ___domain powers and a violation of constitutional rights to due process.