RENO, Nevada (AP) — The Biden administration says it has completed a court-ordered review that should ensure construction continues at a Nevada lithium mine, despite legal challenges brought by conservationists and tribal leaders.

At the same time, in a broader response to recent U.S. court rulings that more strictly interpret a Civil War-era mining law, the Interior Department announced Tuesday it is taking steps to clarify mineral rights under the 1872 law to reflect the “realities of the 21st century.”

The moves come after the 9th U.S. Circuit Court of Appeals blocked a proposed copper mine in Arizona last year. The Appeals Court is considering a related appeal filed by environmentalists and Native American tribes challenging construction of the huge Thacker Pass lithium mine in Nevada near the Oregon line.

Lithium is a key element needed to manufacture batteries for electric vehicles — a centerpiece of President Joe Biden's “clean energy” agenda intended to expedite a transition from fossil fuels to renewable forms of energy.

The 9th Circuit's so-called “Rosemont decision” upended the government’s long-held position that the 1872 Mining Law conveys the same rights established through a valid mining claim to adjacent land for the disposal of tailings and other waste. The 9th Circuit held instead that the company must establish — and the government must validate — that valuable minerals are present under such lands for a claim to exist.

U.S. District Judge Miranda Du in Reno adopted the new standard in a ruling in February that found the U.S. Bureau of Land Management failed to comply with the law when it approved a Canadian company's plan to open the Thacker Pass mine about 200 miles (322 kilometers) northeast of Reno.

Despite that ruling — and over the objections of environmentalists and tribes who now are appealing to the 9th Circuit — Du allowed construction to begin at the mine while the agency provides additional proof the company has the mineral rights necessary to dump waste rock and tailings from the operation on adjacent federal land.

Interior Department officials announced Tuesday that the land management bureau has completed the review necessary to establish mineral rights on the land adjacent to Lithium Americas' project and is convinced it will satisfy Du’s requirement.

A group of Native Americans and some supporters have been staging a protest since last week near the site where the open pit mine is planned. The mine would ultimately be deeper than the length of a football field. They say federal law prohibits construction of the project near where dozens of Paiute tribal members were massacred by the U.S. cavalry in 1865.

The San Francisco-based 9th Circuit has scheduled oral arguments for the Thacker Pass appeal for June 26 in Pasadena, California.

Lithium Americas CEO Jonathan Evans said in a statement after Tuesday's announcement they are “pleased the administration has established a path forward that allows us to resolve the outstanding matters related to the approval of our Thacker Pass project."

Sen. Catherine Cortez Masto, D-Nev., called the “Rosemont decision” misguided and said it defies more than a century of practice on landscapes in the West. She recently introduced a bill with bipartisan support seeking to insulate the mine at Thacker Pass and others from the ruling by essentially adopting language that reverts to the historic interpretation that automatically conveyed established mining rights to the neighboring lands.

An Interior Department official told The Associated Press ahead of Tuesday's formal announcement that the Biden administration doesn’t intend to challenge or appeal the Rosemont decision. The official requested anonymity because they were not authorized to discuss the issue publicly. The department issued a new legal opinion from its solicitor general to provide guidance to mining companies.

The new opinion “will support the timely review of mining proposals on federal lands and is one step of many" Interior is taking to “update guidance for mining companies to reflect the realities of the 21st century,” Deputy Interior Secretary Tommy Beaudreau said in a statement.

Beaudreau is the chairman of the administration's Working Group on Mining Regulations, Laws and Permitting that's expected to offer a list of recommendations sometime this year to make improvements to the antiquated mining law.

Dozens of other mines face similar situations as Thacker Pass, an Interior Department official said Tuesday.

“We are not appealing or challenging Rosemont," a spokesman said. “It makes it clear for the company that if you have a situation like Rosemont or Thacker, you have these options."

Officials analyzed more than 100 of the nearly 500 individual claims and found only eight that don’t have evidence of enough mineralization to justify siting the waste rock dump there, Interior said.

Solicitor General Robert T. Anderson said in his 10-page opinion that the U.S. Bureau of Land Management should not approve a mine operating plan if the record lacks any evidence of valuable mineral deposits on the adjacent land planned for the waste rock dump. But he said the agency is not required to “conduct a validity determination ... if there is some evidence of discovery.”

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Daly reported from Washington.