The 93rd United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, D.C., from January 3, 1973, to January 3, 1975, during the last 18 months of Richard Nixon's presidency, and the first 6 months of Gerald Ford's. This Congress was the first Congress with more than two Senate presidents. After the resignation of Spiro Agnew, Gerald Ford was appointed under the authority of the newly ratified 25th Amendment. Ford became president the next year and Nelson Rockefeller was appointed in his place. The apportionment of seats in the House of Representatives was based on the 1970 United States census. Both chambers had a Democratic majority.

The Endangered Species Act of 1973 is the primary law in the United States for protecting and conserving imperiled species. 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 Supreme Court of the United States described it as "the most comprehensive legislation for the preservation of endangered species enacted by any nation". The purposes of the ESA are two-fold: to prevent extinction and to recover species to the point where the law's protections are not needed. It therefore "protect[s] species and the ecosystems upon which they depend" through different mechanisms. For example, section 4 requires the agencies overseeing the Act to designate imperiled species as threatened or endangered. Section 9 prohibits unlawful ‘take,’ of such species, which means to "harass, harm, hunt..." Section 7 directs federal agencies to use their authorities to help conserve listed species. The Act also 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). The 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 National Marine Fisheries Service (NMFS). FWS and NMFS have been delegated by the Act with the authority to promulgate any rules and guidelines within the Code of Federal Regulations (CFR) to implement its provisions.