HELENA, Mont. - A federal court hearing today could decide how the federal Endangered Species Act is interpreted, and whether the government can use political considerations in choosing how and where a species can be listed under the act, according to people on both sides of the issue.

U.S. District Judge Donald Molloy will hear arguments in Missoula on the U.S. Fish and Wildlife Service's April 2009 decision that designated northern Rocky Mountain gray wolves a distinct population segment, took the wolves off endangered species list and turned over wolf management to Montana and Idaho wildlife officials.

The same decision left federal protections in place in Wyoming, where state law is considered hostile to the wolves' survival. Wyoming law declares almost 90 percent of the state a "predator zone" where wolves can be shot on sight.

Key among the arguments by Defenders of Wildlife, the Greater Yellowstone Coalition and the other plaintiffs is that leaving federal protections in one state while removing them in the other two is a violation of the law that protects wildlife.

"I feel as though this is about the legal standing for the Endangered Species Act," said Earthjustice attorney Douglas Honnold, who is representing the plaintiffs. "It's going to have an impact on virtually every species that's listed."

If the court rules for the Fish and Wildlife Service, the decision will set a precedent allowing the federal government to arbitrarily choose which animals should be protected and where, Honnold said.

The Fish and Wildlife Service says it considered all relevant factors in making the decision and it has the discretion to limit endangered species protections to just that portion of the species' range where it is endangered.

"It's (going to be) a significant ruling by the judge, we believe," said Fish and Wildlife Service spokeswoman Sharon Rose. "It has implications for how a distinct population segment is going to work and how it is interpreted in the Endangered Species Act."

State officials in Montana and Idaho, farm bureaus in those states and the National Rifle Association are among those who have intervened in the case to say the federal government did the right thing.

Montana Attorney General Steve Bullock said the Fish and Wildlife Service has the latitude to leave protections in place for Wyoming's wolves and not in Montana and Idaho because the threat to wolves there comes from Wyoming's management plan, regulations and statutes.

"All of which define political choices, not assessments of the status of a species' health and habitat," Bullock wrote in a court briefing.

"It is allowed under the (act), if not required, to continue to classify wolves in Wyoming as endangered, recognizing the full biological and political recovery of the remainder of the (northern Rocky Mountain) gray wolf population."

In its brief to Molloy, the Greater Yellowstone Coalition disagreed.

"The split means that whether an individual Yellowstone wolf could be killed depends entirely on an arbitrary, non-science-based criterion: whether that wolf happened to be standing in Wyoming or a few feet away in Idaho or Montana at the moment a hunter was present," it wrote.

Wildlife advocates also claim the minimum populations set by the Fish and Wildlife Service are not enough and the states don't have adequate management plans to ensure the wolves aren't wiped out.

Gray wolves were listed as endangered in 1974, after they had been wiped out across the lower 48 states by hunting and government-sponsored poisoning. Following a reintroduction program in the mid-1990s, there are now more than 1,700 wolves in the Northern Rockies: at least 843 in Idaho, 524 in Montana and 320 in Wyoming, with the remainder in parts of Oregon and Washington state.

The plaintiffs cite studies that say well over 1,000 wolves are needed to sustain a wolf population in the northern Rockies, but Idaho and Montana now have the authority to kill hundreds of wolves, even in key dispersal areas.

Ranchers and hunters in those states say the pendulum has swung the other way and they're losing more livestock and game to attacks because there are too many wolves.

Each side is asking Molloy to grant a summary judgment, which could end the court case before it goes to trial. Molloy is expected to rule later this year.