	Introduction

The Endangered Species Act (ESA) (1) provides for the listing and protection of species that are found tobe "endangered" or "threatened" -- species that need conservation efforts because they might becomeextinct. The listing of a species as endangered triggers the prohibitions in the act against "taking"(killing or harming) individuals of the protected species, unless a permit is obtained to takeindividuals incidental to an otherwise lawful proposed action, or unless an exemption for theproposed action is obtained. Unauthorized taking of a listed species can result in civil or criminalpenalties. These prohibitions and potential penalties can affect various activities, including the useand development of land, with attendant economic impacts. Therefore, the extent to which likelyeconomic impacts can be taken into account under the ESA has been of interest. Some parts of theact relate to importation and commercial trading in listed species. (2) This report does not addressthose issues, but discusses the ESA generally and how some of its provisions, aside from thecommercial context, relate to the consideration of economic factors. It will be updated ascircumstances warrant. The Listing Process

The determination of whether a species should be listed as endangered or threatened mustbe based on several factors that relate to the surviving numbers of a species and threats to itscontinued existence, but do not include a consideration of the economic effects of listing. (7) While the origins of threatsto a species may be caused by development or other economic activities, listing determinations areexpressly to be made "solely on the basis of the best scientific and commercial data available." (13)
Therefore, although economic factors are not to be considered in the listing of a species asendangered or threatened, economic factors must be considered when deciding whether and whereto designate critical habitat, and some habitat areas may be excluded from designation based on suchconcerns, unless the failure to designate the habitat would result in the extinction of the subjectspecies.
The Endangered Species Act (ESA) provides for the listing and protection of species that arefound to be "endangered" or "threatened" -- species that might become extinct. The listing of aspecies as endangered triggers the prohibitions in the act against "taking" (killing or harming)individuals of the protected species, unless a permit is obtained to take individuals incidental to anotherwise lawful proposed action, or an exemption for the proposed action is obtained. Unauthorized taking of a listed species can result in civil or criminal penalties. These prohibitionsand potential penalties can affect various activities, including development and use of land, withattendant economic impacts. Therefore, the extent to which likely economic impacts can be takeninto account under the ESA has generated interest and discussion.
The determination of whether a species should be listed as endangered or threatened mustbe based "solely on the basis of the best scientific and commercial data available." ("Commercialdata" here refers to trade data.) The data that may be considered at the listing stage may include factsrelated to a species' population, habitat, distribution, etc., as well as threats to its continued survival,but must not include economic factors.
However, economic factors may be, and in some instances must be, considered in devisingresponses to the listing of a species -- e.g., in the designation of critical habitat, in the process forobtaining an exemption for a particular proposed action from the prohibitions of the ESA, and in thedevelopment of the recovery plan for a listed species. Economic factors also play less direct rolesin the permitting processes.
Parts of the ESA relate to commercial importation and trade in listed species. This reportdoes not address those issues, but rather discusses the ESA generally, aside from the commercialcontext, and how some of its provisions relate to the consideration of economic factors. It will beupdated as circumstances warrant.