TSX- and NYSE-listed Hudbay Minerals is appealing a 2019 district court decision, which overturned approvals issued by the US Forest Service for Rosemont mine, in Arizona, announcing on Monday that it had filed its initial brief with the US Court of Appeals.

The mining company is appealing the July 2019 decision of the US District Court of Arizona, which revoked the US Forest Service’s final record of decision of June 2017, arguing that the court misinterpreted federal mining laws.

The US federal government filed its initial brief last week.

“Today’s filing represents the next milestone in our efforts to correct what we believe is a misinterpretation by the District Court of the current laws and regulations that govern mining operations on public lands,” said Hudbay CEO and president Peter Kukielski.

“We believe, based on the arguments filed by Hudbay and the government, that the appellate court will reverse the District Court’s decision, allowing us to move forward with constructing and operating the Rosemont project.”

Both briefs assert that current law broadly authorises mining-related activities, such as ore processing and tailings storage, to be conducted on open Forest Service lands.

“The District Court’s determination that the Forest Service’s mining regulations do not apply to mining activities unless those activities are conducted entirely on valid mining claims is contrary to plain language readings of the general mining law, as well as Forest Service regulations, which explicitly allow for mining-related activity to occur on lands not covered by any mining claim,” the company argued.

Hudbay’s Arizona business unit VP Andre Lauzon warned in a media statement that, if not reversed, the decision would disrupt the longstanding policy of the US federal government to promote mining on public lands, including within national forests.

Hudbay anticipates a final decision in the appeal process in late 2021.

Once in production, the Rosemont mine is expected to be one of the largest copper mines in the US.

The project has total proven and probable reserves of 537.1-million tonnes grading 0.45% copper, 0.012% molybdenum and 4.58 g/t silver. A technical report completed on the project in 2017 envisages a traditional openpit shovel/truck operation.

The project is expected to produce about 127 000 t/y of copper over the first ten years of operation.

The technical report envisages a mine life of 19 years.