During the listing process, economic factors cannot be considered, but must be " based solely on the best scientific and commercial data available." The 1982 amendment to the ESA added the word "solely" to prevent any consideration other than the biological status of the species. Congress rejected President Ronald Reagan's Executive Order 12291 which required economic analysis of all government agency actions. The House committee's statement was "that economic considerations have no relevance to determinations regarding the status of species."

What word was added to the Endangered Species Act in 1982?