The Rise and Fall of Worst Case Analysis

The National Environmental Policy Act (NEPA) was designed to protect the environment by requiring federal agencies to consider environmental factors in their decisionmaking processes. In 1978, the Council on Environmental Quality (CEQ), as part of its comprehensive review of the NEPA regulations, enacted a regulation requiring federal agencies to address incomplete or unavailable information in their Environmental Impact Statements (EISs). The regulation instructed federal agencies, when addressing "scientific uncertainty" or "gaps in relevant information" regarding significant adverse environmental effects which were "essential to a reasoned choice among alternatives" or "important to the decision," to obtain such information and include it in the EIS. If this information could not be acquired because the "overall costs of obtaining it [were] exorbitant" or "the means for obtaining it were beyond the state of the art," the agency was required to conduct a worst case analysis and indicate the probability of such an occurrence.