An endangered species is one that is likely to become extinct throughout all or part of its geographic range unless steps are taken to prevent its loss. Many of the species currently disappearing are tropical plants and insects that have not even been described by science but whose small ranges are being destroyed by deforestation. These species may contain valuable pharmaceuticals which could lead to cures for diseases, but they are also the irreplaceable products of millions of years of evolution.

The U.S. Endangered Species Act (ESA) protects any endangered species as well as the critical habitat on which it relies. Critical habitat does not necessarily include the entire ecosystem across the species' range. The ESA is the strongest ecological law in the world today because it has the power to restrict or eliminate human impact across an entire species range. Because the economic stakes...