The Purposes, Effects, and Future of the Endangered Species Act's Best Available Science Mandate

Abstract

In recent years, the use of scientific data in administrative decisions has become increasingly contentious. The Endangered Species Act, because it repeatedly calls for consideration of the best available scientific data and has been at the center of a number of fierce disputes, provides a useful case study of the role of science in environmental policy.

To date there has been little explicit analysis of either the reasons for the Act's strong and repeated best available science mandate or the effects of the mandate on the Act's implementation. The mandate could have been intended to increase the substantive accuracy of decisions, to promote political credibility, to alter the terms upon which courts review agency decisions, or to change the decision-making process. Today, the mandate's effect on the substantive accuracy of decisions above the background levels guaranteed by the Administrative Procedure Act appears limited. Its ability to provide political credibility has been eroded by high-profile disputes in which the scientific data supporting decisions has been publicly shown to be thin. It is difficult to tell whether it has had any effect on the outcome of judicial review. Procedurally, the mandate may enhance the influence of career scientific employees in agencies by comparison with that of the political appointees who head the agencies. It could also be interpreted to impose an affirmative data discovery or collection requirement. Early regulations and judicial decisions found just such a requirement, but more recently both implementing agencies and courts appear to have moved away from that interpretation.

Recent proposals to amend the Endangered Species Act have concentrated on imposing additional scientific hurdles to regulation. Those proposals would do little to improve the substantive reliability of agency decisions. Scientific information is and will remain limiting for a large proportion of decisions under the Act. In order to achieve the Act's conservation purposes, the implementing agencies must have the discretion to rely on thin scientific information at the outset. The best available science mandate, which allows the agency to extrapolate from existing data, provides that discretion. But the scientific information available could be put to more effective use, consistent with a robust political process. The agencies should be forced to openly acknowledge the limits of the available scientific data and choices made in the face of uncertainty. They should also be required to take stronger steps to improve the knowledge base over time, so that decisions can become progressively more reliable. These steps, which would not require legislative modification of the Act, could improve both the substance and the political credibility of implementing decisions.