A rendering of the proposed Rosemont copper project, which has faced numerous uphill battles. (Photo: Hudbay Minerals)

Hudbay Minerals Inc. filed an initial brief in federal appeals court to contest a district court ruling that halted construction on the company’s Rosemont copper project in Arizona.

The brief, filed with the U.S. Court of Appeals for the Ninth Circuit, followed one filed by the federal government last week.

Both briefs argued against the District Court of Arizona decision of July 31, 2019, to revoke the U.S. Forest Service’s Final Record of Decision for the project, issued in June 2017.

The district court ruled that Forest Service mining regulations apply only to mining activities on valid mining claims. The project involves mining activities that would occur on public lands and not on mining claims.

The ruling came after a host of environmental organizations, mining opponents and tribes sued to stop the project.

Both briefs held that the district court misinterpreted federal mining laws and Forest Service regulations. According to both briefs, the law and Forest Service regulations authorize mining-related activities on open Forest Service lands.

The briefs argued the Forest Service has authority over mining activities occurring on public lands, and, therefore, the Forest Service decision covers the project.

Hudbay’s brief described the district court decision as unprecedented. “Prior to the District Court’s decision, no court had ever held that a mining plan of operations may only be approved if all mining and mining-related operations will occur exclusively on valid mining claims,” the company reported. “The district court imposed this novel requirement on the Forest Service after misreading both the relevant statutes, which authorize the Forest Service to approve those operations on or off of mining claims.”

Hudbay said the court ignored more than 150 years of precedent. “This decision, if not reversed, will disrupt the longstanding policy of the federal government to promote mining on public lands, including within national forests,” Hudbay Vice President of the Arizona Business Unit Andre Lauzon said.

The $1.9 billion open-pit Rosemont project, sited in the Santa Rita Mountains, was fully permitted and had announced the launch of construction when the district court issued the stop-work order. It was planned to be the third-largest copper mine in the U.S.

The Forest Service environmental review and decision involved 17 cooperating agencies.