Endangered Species Act (ESA)

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The Endangered Species Act (ESA) (7 U.S.C. § 136, 16 U.S.C. § 1531 et seq.) is designed to protect species from extinction as a "consequence of economic growth and development untempered by adequate concern and conservation."  This act is designed to protect both the species and “the ecosystems on  which endangered species and threatened species depend.”


The ESA protects only those species that are listed as “endangered” or “threatened”. A species can be listed in two ways. The United States Fish and Wildlife Service (FWS) or National Oceanic and Atmospheric Administration  (NOAA, which includes the National Marine Fisheries Service - NMFS) can directly list a species through its candidate assessment program, or an individual or organizational petition may request that the FWS or NMFS list a species.

To be considered for listing, the species must meet one of five criteria (section 4(a)(1)):

  1. There is the present or threatened destruction, modification, or curtailment of its habitat or range.
  2. An overutilization for commercial, recreational, scientific, or educational purposes.
  3. The species is declining due to disease or predation.
  4. There is an inadequacy of existing regulatory mechanisms.
  5. There are other natural or manmade factors affecting its continued existence.

Potential candidate species are then prioritized, with "emergency listing" given the highest priority. Species that face a " significant risk to their wellbeing" are in this category.

Federal Agency Actions

Under §7(a)(2), no federal agency may authorize, fund or carry out any action likely to threaten or harm the existence of an endangered / threatened species (or harm their habitat).
According to the Supreme Court, the plain intent of Congress in enacting the ESA was to protect species from extinction at any cost.  Thus, Federal Agencies may not consider the cost in making decisions. This was made evident in TVA v. Hill – 437 U.S. 153 (1978) where the courts enjoined a dam that was essentially complete (and had cost almost $80 million) because opening the dam would have endangered the snail darter perch.
Although this aspect does not apply directly to private landowners, large-scale development, logging and mining projects usually require a federal permit, and so become subject to critical habitat regulation.

Private Actions

Under §9(a)(1), no one, public or private, can “take” an endangered species of fish or wildlife.  “Take” has been broadly defined to include “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or collect.”  Furthermore, FWS has declared that “harm” includes “significant habitat modification or degradation.”  Thus, the habitat as well as the endangered animal is protected from private action.  This interpretation was controversial but was upheld in Babbitt v. Sweet Home - 515 U.S. 687 (1995).

Exemptions and Exclusions

Although the ESA appears to provide rigid protection of endangered species, various amendments have created flexibility in the statute, with the result of less protection. Examples:

  • Exemptions
    • In response to TVA v. Hill, an agency may now seek an exemption from the Endangered Species Committee (sometimes referred to as “the God Squad” for their ability to determine an animal’s fate).
  • Incidental Take Permits. 
    • Under §10(a), the FWS may permit an otherwise unlawful taking if
      • The taking is merely incidental to an otherwise lawful activity and
      • The permit applicant has devised an acceptable habitat conservation plan (HCP).
  • Safe Harbor. 
    • Under the "enhancement of survival" provision of Section §10(a)(1)(A), a landowner and FWS may enter into a voluntary agreement where the landowner agrees to alter the property to benefit or even attract a listed or proposed species in exchange for assurances that the FWS will permit future "takes"above a pre-determined level. 
    • This may be done in addition to an incidental take permit.
  • The "No Surprises" rule. 
    • This is meant to give the landowner certainty and protection against "unforeseen circumstances." 
    • Should the landowner's efforts to prevent or mitigate harm to the species fall short, the government will maintain the incidental take permit, and will pay for any new habitat or actions needed.

See also: Environmental Law


  • Endangered Species Act
  • TVA v. Hill
  • Babbit v. Sweet Home

[Last updated in November of 2022 by the Wex Definitions Team]