Justice Department lawyers filed a motion last week for a stay in the proceedings until Congress restores both agencies' appropriations.
Horse advocates claimed it was a ploy to keep them from securing a court order to stop the shipment of animals to a Mississippi contractor they say has a history of reselling them for slaughter.
U.S. District Judge Miranda Du didn't directly address that claim in rejecting the government's request. But she ruled Bonnie Kohleriter of California and Laura Leigh of Nevada have a right to argue their First Amendment right in court to have access to the horses to ensure their safety before the animals are shipped from a temporary holding facility in northwest Nevada where they've been held since more than 400 were rounded up last month at the Sheldon National Wildlife Refuge.
"If a stay is granted, the issue set for the ... hearing may be moot by the time the appropriation issue is resolved," Du wrote in a three-page ruling issued late Friday.
The horse advocates argue the Interior Department's Fish and Wildlife Service has illegally prohibited them from viewing the horses at the holding facility, where they claim some have been mistreated.
Du noted the 9th U.S. Circuit Court of Appeals recently ruled in another case brought by Leigh—a photographer and leader of the group Wild Horse Education—that the "courts have a duty to conduct a thorough and searching review of any attempt to restrict public access."
"Even if shipment of horses is halted during the period of the government shutdown, and horses remain at the temporary holding facility through the requested stay, plaintiffs' First Amendment right of access to viewing may be abridged given the ongoing nature of the alleged violation," Du wrote.