<Tr> <Th_colspan="2"> United States Supreme Court cases </Th> </Tr> <Tr> <Td_colspan="2"> Lujan v. Defenders of Wildlife, 504 U.S. 555 (1992) Tennessee Valley Authority v. Hill, 437 U.S. 153 (1978) </Td> </Tr> <P> The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq .) is one of the few dozens of US environmental laws passed in the 1970s, and serves as the enacting legislation to carry out the provisions outlined in The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Designed to protect critically imperiled species from extinction as a "consequence of economic growth and development untempered by adequate concern and conservation", the ESA was signed into law by President Richard Nixon on December 28, 1973 . The U.S. Supreme Court found that "the plain intent of Congress in enacting" the ESA "was to halt and reverse the trend toward species extinction, whatever the cost ." The Act is administered by two federal agencies, the United States Fish and Wildlife Service (FWS) and the Commerce Department's National Marine Fisheries Service (NMFS). </P> <P> Listing status and its abbreviations used in Federal Register and by federal agencies like the U.S. Fish and Wildlife Service: </P>

When was the endangered species act originally passed and what was its purpose
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