Understanding Environmental Law: The ESA
- Alyna Sigel
- Apr 17
- 4 min read
Alyna Sigel

Established in 1973, the Endangered Species Act, or ESA, is one of the most influential pieces of environmental legislation to date. To better understand the basics of the Endangered Species Act, it is necessary to first break down Section 3, or the definitions section.
While knowing all of the definitions is beneficial to fully understanding the details of this statute, there are a few that are still necessary for understanding the basics. An endangered species is defined as, “any species which is in danger of extinction throughout all or a significant portion of its range,” with additional qualifications for insects. Furthermore, the term “person” is defined to include any “individual, corporation, partnership, trust, association, or any other private entity…” or more simply, anyone. Depending on relevance to the species, the term Secretary refers to the Secretary of the Interior, the Secretary of Commerce, or the Secretary of Agriculture. Finally, a term often used in discussing the statute is “take.” A “take” is defined as, “to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct.” These definitions are most essential in comprehending the meaning and language of the Endangered Species Act.
For a species to be recognized as endangered under the ESA, the Secretary must follow the outlined basis for determinations in Section 4 and list the species as endangered. Through Section 5, the Secretary also has the power and responsibility to conserve species, including those listed as endangered.
The true action of the act is derived from Section 7 and Section 9. Section 7 sets obligations for federal agencies. This prevents federal agencies from taking actions that are likely to discontinue the existence of any species listed as endangered. This can require bringing in experts for evaluation and assistance. However, to better understand this section, it is important to have a background on TVA v. Hill. Tennessee Valley Authority was in the process of building a dam, as passed by Congress before the ESA. Environmental activists opposing the dam found that rare snail darters lived in the river and the species was soon registered as endangered under the ESA. TVA was brought to court for violation of the ESA, and though the district court ruled that the completion of the dam violates the act, they did not issue an injunction because the dam was nearly finished. The plaintiffs appealed and the Supreme Court of the United States took the case. While SCOTUS held that it would be a violation, dissenting opinions later resulted in the creation of The Endangered Species Committee, or the “God Squad”. This amendment to the ESA allows for case-by-case judgment but this committee when federal action is stopped by the statute, potentially allows for leeway. The effect was the eventual completion of the dam, though the case continues to set precedents for the implementation of the ESA to halt federal actions.
Section 9 also applies to federal agencies, but extends to include all persons, as defined in Section 3. Similarly to Section 7, it is meant to ensure that no persons take actions that are likely to take, as defined by Section 3, an endangered species.
In interpreting each of these action sections, there is an inherent application of proximate cause. Proximate cause requires that the consequences of the action taken are reasonably foreseeable. In terms of the ESA, the average person must be able to reasonably foresee that the action would negatively impact an endangered species. If there is no proximate cause, then there is not a violation of the ESA.
This leads to an important environmental law case, Babbitt v. Sweet Home. Logging in a forest housing the endangered cockaded woodpecker resulted in intense habitat destruction, which was found to be a violation of the ESA. The understanding of proximate cause in this case was noted in the decision, solidifying the importance of causation in interpreting the statute.
Additionally, this case held that habitat destruction harms a species and is therefore considered a take and a violation.
However, habitat destruction is not an end-all be-all. To fully understand the basics of the Endangered Species Act, one must know the Section 10 amendment allowing for Habitat Conservation Plans. Though not included in the original act, it provides an option for continuing potentially harmful activities without adversely threatening an endangered species. If one can overwhelmingly prove, with scientific evidence, that an offsetting positive measure can and will be taken alongside habitat destruction, the destructive action may be able to continue. Applying to any non-federal party, there is a multistep process and paperwork requirements that may be pursued before habitat destruction activities. This incentivizes sustainable economic development that allows for the continued protection of species.
As one of the most influential statutes in terms of environmental protection in the United States, it is crucial to understand the basics of the Endangered Species Act. Not only is this act essential in environmental law, but it also exemplifies the role that activists can have in making real, tangible changes to protect endangered species and the environment as a whole.
Citations
CaseBriefs. “Babbit v. Sweet Home Chapter of Communities for a Great Oregon | Case Brief for Law Students | Casebriefs.” Casebriefs.com, 2018, www.casebriefs.com/blog/law/property/property-keyed-to-sprankling/an-introduction-to-environmental-law/babbit-v-sweet-home-chapter-of-communities-for-a-great-oregon/.
Green, William Crawford. “Tennessee Valley Authority v. Hill | EBSCO.” EBSCO Information Services, Inc. | Www.ebsco.com, 2023, www.ebsco.com/research-starters/law/tennessee-valley-authority-v-hill. Accessed 23 Mar. 2025.
Levey, Brian R., and Andrew J. Turner. “Streamlining NEPA and ESA Reviews: Importance of the Scope of Analysis.” @HuntonAK, 27 Feb. 2020, www.hunton.com/the-nickel-report/streamlining-nepa-and-esa-reviews-importance-of-the-scope-of-analysis0. Accessed 23 Mar. 2025.
NOAA Fisheries. “Endangered Species Act.” NOAA, 2023, www.fisheries.noaa.gov/national/endangered-species-conservation/endangered-species-act.
Sheikh, Pervaze A. “Endangered Species Act (ESA): The Exemption Process.” Congress.gov, 2025, www.congress.gov/crs-product/R40787. Accessed 27 Jan. 2017.
U.S. Fish & Wildlife Service. “Habitat Conservation Plans | U.S. Fish & Wildlife Service.” Www.fws.gov, www.fws.gov/service/habitat-conservation-plans.