The Endangered Species Act (ESA) may be the most powerful environmental law in the United States. Enacted in 1973, the ESA prohibits any actions that may cause harm to endangered plants and animals or the ecosystems upon which they depend. But although more than 1,200 species are protected under the Act, most remain in peril. The ESA may have saved some species from the brink of extinction, but there is little evidence it is working as intended to...