Acting with No Regret: A Twenty-Five Year Retrospective of Marsh v. Oregon Natural Resources Defense Council

Abstract

In Marsh v. Oregon Natural Resources Defense Council, 490 U.S. 360, 371 (1989), the Supreme Court held that the National Environmental Policy Act of 1969 (NEPA) requires agencies to supplement environmental impact statements (EIS) upon discovering “new and significant” information. In the 25 years since Marsh, courts have often considered whether an agency should be enjoined from acting because its EIS does not adequately consider new and significant information. But, because “new and significant” information is not precisely defined, and because the circuit courts of appeals are split on how to review supplementation claims, NEPA practitioners face considerable uncertainty about when supplementation is required. This article provides NEPA practitioners with a roadmap for supplementation by (1) reviewing cases to determine what information is actually “new and significant” in practice and (2) examining what procedural steps an agency should take to evaluate new information. Generally, this article concludes that new information showing a previously-unconsidered but severe environmental impact will be significant but information that is similar to that previously considered, is vague or speculative, does not undermine important assumptions in the EIS, challenges common sense, or will be considered in future environmental reviews is not significant. And when considering new information, agencies should document their review, consult with established experts, directly respond to the new information, seek public input, and hire outside experts, when necessary. Armed with this roadmap, NEPA practitioners can better define, examine, and address information and its significance. With a better understanding of what information is significant, NEPA practitioners can comply with NEPA and Marsh and act with no regret.