The wolves gained protected species status in the mid-1970s and about 20 years later, U.S. wildlife officials submitted a plan to reintroduce the wolf into the park, starting with 31 wolves let loose in Idaho.
As biologists and rangers approach the Nez Perce pack's chain-link pen deep in the park's interior, they hear a surprising sound -- a wolf barking from outside.
The case stems from a December 1997 ruling by Wyoming District Court Judge William Downes that the wolf reintroduction program in Yellowstone and central Idaho is illegal and that all wolves in the park must be removed.