Endangered Species Act
The Endangered Species Act (ESA) of 1973 provides a framework for the conservation of threatened and endangered plants and animals and their habitats. The law requires federal agencies, in consultation with the U.S. Fish and Wildlife Service and/or the U.S. National Oceanic and Atmospheric Administration / National Marine Fisheries Service, to ensure that actions they authorize, fund, or carry out are not likely to jeopardize the continued existence of any listed species or result in the destruction or adverse modification of designated critical habitat. The law also prohibits any non-permitted private action that causes the "taking" of any listed species or their designated critical habitat. Import, export, interstate, and foreign commerce of listed species are also generally prohibited.
The most common applications of the ESA for industry are Section 7 consultations for projects with a federal nexus (e.g. a permit from a federal agency), and Section 10 Habitat Conservation Plans (HCP) for private actions that do not have a federal nexus but may affect a listed species or their designated critical habitat.
For more information: http://www.fws.gov/endangered/laws-policies/index.html.
PDF of ESA, from U.S. Senate (47 pp, 136K)
EPA's Endangered Species Protection Program Home Page
USFWS’s Endangered Species Program