A federal judge ordered the U.S. Fish and Wildlife Service to take its wolverine ruling back to the drawing board, and this time, apply the best-available science.

On Monday, Missoula federal district Judge Dana Christensen was stern and meticulous in his criticism of the 2014 USFWS decision not to list the wolverine as threatened. In his 85-page ruling, he said the USFWS decision was “arbitrary and capricious” because it purposely ignored the best-available science on how climate change and genetic isolation would negatively affect the elusive carnivore.

“It is (my) view that if there is one thing required of the Service under the (Endangered Species Act), it is to take action at the earliest possible, defensible point in time to protect against the loss of biodiversity within our reach as a nation. For the wolverine, that time is now,” Christensen concluded.

The plaintiffs – 24 conservation groups including WildEarth Guardians – were elated.

“The judge can’t say, ‘You have to protect the species,’ but he basically said that,” said Bethany Cotton of WildEarth Guardians. “The (Fish and Wildlife) Service can’t say, ‘We don’t know enough’ – they’re supposed to give the species the benefit of the doubt.”

According to court documents, conservation groups had doggedly pursued protection for the wolverine since 1994, and in 2013, the USFWS finally announced its intent to list the wolverine as threatened because climate change was reducing its habitat and connectivity between populations. Staff wrote a recovery plan and had begun designating areas of critical habitat in the mountains of the West.

But over the following year, after receiving 118,000 public comments and aggressive pushback from seven Western states including Montana, USFWS Regional Director Noreen Walsh first questioned and then reversed that decision in August 2014. Her justification was there wasn’t enough information to know what would happen to wolverines.

Frustrated by the reversal, the two-dozen conservation groups sued in October 2014 on the basis that the reversal was unsupported by most scientists and that Walsh could not ignore the best-available science by demanding better science.

Five of seven scientists reviewing the data concluded in May 2013 that the science supported the fact that climate change threatened wolverine survival.

Then a year later, a panel of nine experts agreed on the validity of the two modeling studies that both predicted that the depth of spring snowpack would continue decreasing and affect wolverines that depend on deep snow for their dens. If anything, while the models couldn’t be exact, the experts said the models actually underestimated the loss of snow. Plus, no other studies showed that less snow wouldn’t affect wolverines.

Shawn Sartorius of the USFWS Montana Ecological Service Office questioned his boss’ intent to reverse the decision saying that not knowing exactly why wolverines need deep snow didn’t diminish the fact they need it. He said it would be very difficult to learn why they need it with only 300 wolverines roaming the western U.S.

Still, Walsh ignored the majority of her own scientists and gave more credence to comments criticizing the two studies made by state wildlife agencies, even though, Christensen noted, none of the agencies presented any findings countering the studies.

Christensen pointed out that internal documents showed that states were more politically motivated by resistance to perceived federal oversight and the pressure to maintain trapping opportunity. Montana Fish, Wildlife & Parks allowed trappers to kill five wolverines a year until January 2013.

“Montana’s attacks … are particularly weak and unsavory. Not only did Montana cavalierly dismiss the study as a "hypothesis," breezing right by its well-supported conclusions, but FWP accused the Service biologists of cooking the science in favor of listing with the intent of receiving additional funding,” Christensen wrote.

Christensen also chided the USFWS for not considering small population size and the resultant inbreeding as being a threat to wolverines. He pointed out that the agency’s own documents say only 250 to 300 wolverines reside in the U.S. and maybe only 35 pairs breed a year. But the USFWS also said a healthy population needs at least 500 individuals and 400 breeding pairs to avoid loss of genetic diversity or inbreeding. Even without the threats of climate change, the looming effects of inbreeding should be enough to list the wolverine, Christensen said.

Christensen did not side with the conservation groups on assertions that the USFWS ignored the effects of development and trapping or failed to consider whether regulatory mechanisms were adequate to protect the wolverine. He merely said the agency could reconsider those while it was reevaluating the climate change and inbreeding questions.

The judge’s decision now starts the clock on another 12-month finding, the third in eight years.