DENVER — The federal government asked an appeals court Wednesday to overturn an order that bars the release of endangered wolves in New Mexico without the state’s permission, a skirmish in a broader battle over states’ rights and the Endangered Species Act.
New Mexico and 18 other states argue that the law requires the U.S. Fish and Wildlife Service to cooperate with them on how endangered species are reintroduced within their borders. Federal attorneys counter that the law allows the agency to go around a state, if necessary, to save a species.
Many of the arguments attorneys made to the 10th Circuit Court of Appeals in Denver on Wednesday focused on the legality of the court order restricting the release of more wolves, not the broader issue of the states’ role in restoring endangered species.
But in hundreds of pages of court filings, the states and the federal government staked out opposing positions on who has the final say.
The fight is unfolding amid uncertainty about the future of the Endangered Species Act. Congress and the White House will both be controlled by Republicans who generally see it as an impediment to jobs and economic development.
And even if the court sides with the Fish and Wildlife Service, it’s not clear whether president-elect Donald Trump’s administration will continue to fight after he takes office.
The dispute before the 10th Circuit is over a Fish and Wildlife Service program to restore the Mexican gray wolf to parts of its original range in New Mexico and Arizona.
New Mexico has multiple complaints about the way the program is managed, and in 2015 it refused to issue a permit to Fish and Wildlife to release more of the predators in the state. New Mexico also announced it might sue the agency.
Fish and Wildlife decided to release more wolves anyway, citing an urgent need to expand the wild population to prevent inbreeding. New Mexico officials went to court, and a federal judge in New Mexico issued a preliminary injunction last year blocking further releases while the dispute is resolved.
At Wednesday’s hearing, Justice Department attorney Rachel Heron argued against the state’s rights position, saying the Interior Department — Fish and Wildlife’s parent agency — is required by law to protect the wolves.
A coalition of environmental groups, led by Defenders of Wildlife, intervened on Interior’s side, arguing the state’s interpretation would wrongly give the state veto power over measures to save a federally protected species.
New Mexico state attorney Matthias L. Sayer told the judges that Fish and Wildlife had made it difficult for the state to manage big game because of uncertainty about how many wolves — which prey on big game — would be released.
But one of the judges, Scott Matheson Jr., questioned whether New Mexico could show definitively that it would be harmed by the release of more wolves, and how much harm it would suffer.
The three judges who heard the case did not say when they would decide. Appeals court judges generally take weeks or months to issue a ruling.
Reintroducing wolves is always contentious because they sometimes attack domestic livestock as well as wild game. Last year, the Interior Department’s internal watchdog said Fish and Wildlife had not fulfilled its obligation to remove Mexican gray wolves that preyed on pets and cattle.
The Mexican wolf program has had other problems, including multiple failed attempts to update the original 1982 recovery plan. Fish and Wildlife has agreed to produce a new plan this year to settle a lawsuit filed by conservation groups.
New Mexico officials also complain that federal officials tripled the target number of wolves in the wild — from about 100 to 300 — without sufficient justification.
Only about 100 Mexican gray wolves live in the wild. They nearly disappeared in the 1970s, and the federal government added them to the endangered species list in 1976. The U.S. Fish and Wildlife Service began reintroducing them in New Mexico and Arizona starting in 1998.