"The adequacy of the science supporting implementation of the Endangered Species Act (ESA) is receiving increased congressional attention. While some critics accuse agencies responsible for implementing the ESA of using 'junk science,' others counter that decisions that should rest on science are instead being dictated by political concerns. Under the ESA, certain species of plants and animals (both vertebrate and invertebrate) are listed as either 'endangered' or 'threatened' according to assessments of the risk of their extinction. Once a species is listed, powerful legal tools are available to protect the species and its habitat. Efforts to list, protect, and recover threatened or endangered species under the ESA can be controversial. Some of this controversy stems from the substantive provisions of this law, which can affect the use of both federal and nonfederal lands. The scientific underpinnings of decisions under the ESA are especially important, given their importance for species and their possible impacts on land use and development. […] Several bills affecting science as used in the ESA have been introduced in recent Congresses, but to date none have been enacted. Legislative activity in the 109th Congress is summarized in CRS [Congressional Research Service] Report RL33468, 'The Endangered Species Act (ESA) in the 109th Congress: Conflicting Values and Difficult Choices'. This report provides a context for evaluating legislative proposals through examples of how science has been used in selected cases, a discussion of the nature and role of science in general, and its role in the ESA process in particular, together with general and agency information quality requirements and policies, and a review of how the courts have viewed agency use of science. This report will be updated as events warrant."
CRS Report for Congress, RL32992