## Facts

- Environmental plaintiffs petitioned the U.S. Fish and Wildlife Service (FWS) to list the Queen Charlotte goshawk as threatened or endangered under the Endangered Species Act (ESA).
- The ESA directs that listing determinations be made “solely on the basis of the best scientific and commercial data available.”
- Plaintiffs contended that the best available evidence supported listing; the government contended that the available evidence did not show the species was threatened or endangered.
- The parties agreed the scientific record was sparse and that any population assessment would necessarily rely on estimates rather than a complete count.
- The district court did not decide whether FWS’s position was lawful on the existing record; instead, it remanded with instructions that FWS conduct an on-site population count.
- The government appealed, arguing the ESA does not authorize a court to require an on-site population count as a prerequisite to a listing decision.

## Issues

1. Whether the ESA’s requirement that listing decisions be made on the “best scientific and commercial data available” obligates FWS to conduct an on-site population count when existing data are sparse and estimate-based.
2. Whether a reviewing court may order FWS to gather new field data rather than review the agency’s decision based on the existing administrative record.

## Decision

- The D.C. Circuit reversed the district court’s remand order requiring an on-site population count.
- The court held the ESA does not require FWS to conduct independent studies or actual population counts before making a listing determination.
- The court remanded to the district court to consider the parties’ positions and the legality of the agency’s decision based on the available evidence and the ESA standard.

## Legal Principles

- Under 16 U.S.C. § 1533(b)(1)(A), ESA listing decisions must be made “solely on the basis of the best scientific and commercial data available,” meaning the best data currently accessible, not the best data that could be generated through further research.
- The “best available data” standard permits agency decisions on imperfect or incomplete records when better data are not available at the time of decision.
- Courts reviewing ESA listing decisions must evaluate the agency’s reasoning on the administrative record; they may not compel the agency to conduct new fieldwork to improve the evidentiary record as a condition of review.

## Conclusion

The D.C. Circuit held that the ESA’s “best available” data requirement does not authorize courts to require FWS to perform on-site population counts where data are limited; the proper task is to review the agency’s listing determination on the existing record under the ESA’s statutory standard.


Sw. Ctr. for Biological Diversity v. Babbitt, 215 F.3d 58 (D.C. Cir. 2000)