A federal judge on Friday threw out an Obama administration decision to remove the gray wolf population in the western Great Lakes region from the endangered species list – a decision that will ban further wolf hunting and trapping in three states.

The order affects wolves in Michigan, Minnesota and Wisconsin. The US Fish and Wildlife Service dropped federal protections from those wolves in 2012 and handed over management to the states.

US District Judge Beryl Howell in Washington, DC, ruled Friday the removal was “arbitrary and capricious” and violated the federal Endangered Species Act.

Unless overturned, his decision will prohibit further wolf hunting and trapping in the three states, all of which have had at least one hunting season since protections were removed. More than 1,500 Great Lakes wolves have been killed since federal protections were removed, said Jonathan Lovvorn, senior vice president of the Humane Society of the United States. The group filed a lawsuit that prompted Howell’s ruling.

“We are pleased that the court has recognized that the basis for the delisting decision was flawed, and would stop wolf recovery in its tracks,” Lovvorn said.

Fish and Wildlife Service spokesman Gavin Shire said the agency would issue a statement shortly. There was no immediate reaction from officials in the three states.