Any person or entity may petition the agencies to consider a plant or animal species for possible listing and protection under the Endangered Species Act (ESA).

Although the U.S. Fish and Wildlife Service (FWS) or the National Oceanic and Atmospheric Administration Fisheries (NOAA Fisheries) can choose to consider a species for listing on their own, petitions filed by individuals or organization most often initiate consideration.

Federal law gives these two agencies 90 days to review each petition and issue a 90-day finding:

  • An agency may decide that there is not substantial information in the petition to indicate that a species' listing may be warranted.
  • If the agency finds that there is substantial information in the petition that listing may be warranted, the listing process continues.

If it determines that the petition presents substantial information that listing may be warranted, the agency has 12 months to complete a "status review" for the species. FWS typically begins that process by preparing a Species Status Assessment. This assessment evaluates scientific information regarding the biological status of the species under consideration, as well as its prospects for viability over time.

During the 12-month review period, members of the public can file written comments on the species’ status. After completing the 12-month review, the agency issues a finding that:

  • the evidence does not support a need for listing;
  • the evidence supports a need for listing; or
  • the evidence supports a need for listing, but the issuance of a final rule is precluded by other pending proposals. If this finding is made, the species is placed on a Candidate List and will be re-evaluated annually for possible listing in the future.

If the 12-month review finding is for immediate listing, the agency will publish a proposed rule for listing in the Federal Register for comment. FWS will provide notice of the finding and hold one public hearing if any person requests it.

If the agency determines that the proposed action is not justified, it must withdraw the proposed regulation and announce its decision in the Federal Register.

If the agency decides to list the species, it publishes a final rule in the Federal Register.

Any person or entity can take legal action to challenge a listing determination in federal court. The agency decision can be set aside only if the court determines that the agency's actions were arbitrary, capricious, an abuse of discretion or otherwise not in accordance with law.