The Endangered Species Act (ESA), now nearly 20 years old, remains one of the more controversial pieces of legislation ever enacted by Congress. To many, it is the most important and noblest environmental law on the books; to others, it is among the most onerous. Nearly 1,300 plant and animal species are listed under the act as either endangered or threatened in the U.S., and powerful legal tools are at the disposal of government agencies in charge of protecting them and their habitat. But the use of a number of those tools depends on scientific evidence--
the proof in the pudding of the ESA and, lately, the subject of much debate.
This article was originally published with the title Under the Microscope.