Kevin Clifford, Associated Press
With cows seen in the background, a coyote searches for food on a ranch located on Carson River Road in Carson City, Nev., on Sunday, Oct. 28, 2007.

RENO, Nev. — A U.S. appeals court has breathed new life into a conservation group's legal battle in Nevada aimed at shutting down a Depression-era government program that spends more than $100 million a year to subsidize the killing of predators that threaten livestock.

The 9th Circuit Court of Appeals panel recently overturned a 2013 ruling by a federal judge in Reno who threw out most of the lawsuit filed by the Colorado-based WildEarth Guardians.

The lawsuit claims the U.S. Department of Agriculture's Wildlife Services is acting illegally because it relies on scientific and environmental data that is decades old. They want the program suspended until the underlying data is more current.

Judge Miranda Du had concluded the harm cited by the conservationists would not be alleviated by halting the operations in Nevada because the state has said it would carry out the killings of coyotes, mountain lions, ravens and other predators itself.

But the three-judge panel in San Francisco said in the new opinion that Du's conclusion was "speculative at best" and ordered her to reconsider the case.

"Any independent predator damage management activities by Nevada are hypothetical rather than actual," Circuit Judge Michelle T. Friedland wrote Aug. 3.

The Wildlife Services program has given money to Nevada and other states across the West for more than 80 years.

Bethany Cotton, wildlife director for WildEarth Guardians, said it's a critical ruling.

"For decades, Wildlife Services has operated in the shadows as though it were above the law," Cotton said.

Du has not yet set a briefing schedule for the case to continue in Reno.

USDA officials did not immediately respond to requests for comment.

Officials for the Nevada Farm Bureau Federation and Nevada Cattlemen's Association said they were disappointed and disagreed with the circuit court ruling.

The "predator control program not only benefits the livestock industry, but it benefits wildlife sustainability as well," said Ron Torell of Elko, president of the cattlemen's group. He said sage grouse specifically benefit from reductions in the population of coyotes, which sometimes feed on the birds, and ravens, which sometimes eat their eggs.

The conservationists said the program that spent $127 million to exterminate more than 5 million animals in 2010 should be suspended nationally until USDA updates its scientific analysis that's based largely on an environmental impact statement conducted in 1994.

Cotton said most of the science the program relies on dates to the 1970s and 1980s and has largely been disproven by recent research.

"For example, peer-reviewed science shows that indiscriminant killing of coyotes triggers a biological response that actually leads to an increase in the coyote population," she said. She said a better way to protect sage grouse from coyotes — and their eggs from ravens — is to enforce livestock grazing standards that prevent overgrazing that eliminates grass and sage brush the birds need for cover.

The conservationists said in their appeal that Nevada doesn't have the resources to continue all the work in a state where federal officials spend $1.5 million to kill about 6,000 coyotes annually. They cited state documents supporting their view, and a Nevada Department of Wildlife official acknowledged earlier they probably were right.

"We wouldn't have the manpower," NDOW spokesman Chris Healy told AP at the time. "They are in some wild places in Nevada doing that kind of predator work where we have zero personnel. We already have a full plate."

Judge Du concluded a Nevada member of the group, Don Molde, legally established actual harm as a result of a reduction in his ability to view coyotes, mountain lions and ravens. But she agreed with the government's argument that "there's no relief they can obtain that would redress their alleged injury."

Andrew E. Wetzler, wildlife conservation director for the Natural Resources Defense Council, said the consequences of the appellate ruling "are hard to understate."

"If USDA had prevailed, it would have been virtually impossible to ever challenge any predator management plan undertaken with a state or local government in federal court," he wrote on the group's staff blog. "All Wildlife Services would have to do is to get a letter from the state or locality saying: 'we would do this anyway."