JUDICIAL REVIEW OF SCIENTIFIC UNCERTAINTY IN CLIMATE CHANGE LAWSUITS: DEFERENTIAL AND NONDEFERENTIAL EVALUATION OF AGENCY FACTUAL AND POLICY DETERMINATIONS.

Scientific determinations are often at the heart of environmental disputes. When those disputes take the form of litigation, the courts may be called on to determine whether an administrative agency's treatment of the science warrants deference. For several reasons, judges are inclined to apply deferential review to agency factual and science-based policy determinations. Most judges are not trained in the language and methods of science. They may be reluctant to intervene on matters on which their lack of expertise risks producing uninformed judgments. If a statute delegates to an agency the responsibility of making those determinations, courts may be loath to usurp that authority by substituting their judgment for the agency's. If the statutory delegations authorize agencies to premise their decisions on the best available information, courts may regard that authorization as a signal not to take agencies to task for failing to do the impossible. Those mandates reflect a congressional judgment that agency determinations should pass judicial muster even if they fall short of conclusiveness, which may be impossible to achieve. Finally, when technical issues arise in the context of uncertainty at "the frontiers of scientific knowledge," the Supreme Court has warned judges that highly deferential review is required. This Article describes a study analyzing cases decided by the federal courts over a period of thirty years that presented issues involving scientific uncertainty tied to climate change that arose under two key environmental statutes, the National Environmental Policy Act and the Endangered Species Act. The Article provides both quantitative and qualitative analyses of those cases, focusing on ascertaining the factors that drove courts to apply either deferential or non-deferential review. We found, as might be expected, that the courts applied deferential review in the majority of climate change cases arising under these two laws that presented disputes in which litigants challenged agency resolution of factual or policy matters characterized by scientific uncertainty. In the remaining cases, however, the courts, applying the arbitrary and capricious standard of judicial review, refused to defer, engaging instead in relatively rigorous review of agency science. They did so for any one of several reasons, including irrationality in agency reasoning, incomplete analysis of record science, evidentiary shortcomings, and end result-oriented reasoning. These practices induced courts to reject rote acceptance of agency pleas for deference to their scientific expertise. The Article concludes by suggesting further studies that may be useful in understanding how courts can be expected to strike the balance between deferential review and insistence that agencies provide adequate reasons for their actions in contexts of scientific uncertainty. [ABSTRACT FROM AUTHOR]