US Supreme Court rejects Apache appeal to block Rio Tinto’s Resolution mine

Decision paves way for one of the largest copper mines in North America amid religious freedom concerns.

The US Supreme Court on Tuesday rejected an appeal from the advocacy group Apache Stronghold, effectively clearing a major legal obstacle for the advancement of the Resolution Copper project in Arizona. The controversial mine is a joint venture between mining giants Rio Tinto (ASX, LON, NYSE: RIO) and BHP (ASX: BHP).

Apache Stronghold, which includes members of the San Carlos Apache Tribe and environmental advocates, sought to overturn a lower court ruling that upheld a federal land swap enabling the mining companies to acquire Oak Flat—sacred land in eastern Arizona central to Apache religious practices.

The Supreme Court's decision comes after a federal judge temporarily blocked the land transfer on May 8, pending the outcome of the appeal. With the top court’s refusal to hear the case, that barrier has now been removed, though further environmental and administrative steps remain.

A mine of strategic importance

Resolution Copper, 55% owned by Rio Tinto and 45% by BHP, is set to become the largest copper mine in North America and holds the world’s third-largest known copper deposit. Once operational, the project could supply more than 25% of the United States' copper demand for decades. The two companies have already invested over $2 billion in exploration, planning, and infrastructure.

The project's supporters argue that its development is critical for securing domestic copper supply at a time of accelerating demand driven by clean energy technologies, electric vehicles, and infrastructure growth.

Cultural and legal tensions

Apache Stronghold first filed suit in 2021, claiming that the mine's development violates constitutional rights to religious freedom and breaches an 1852 treaty guaranteeing Apache land protection. According to the group, the destruction of Oak Flat—referred to as Chi’chil Biłdagoteel—would devastate a sacred site used for ceremonies, including traditional rites of passage for Apache girls.

“This decision is a grave injustice to Native peoples and our constitutional rights,” the group said in a statement following the ruling.

The land exchange was authorized by Congress in 2014 as part of a defense spending bill signed by President Barack Obama. It allows Rio Tinto and BHP to swap private lands for control over Oak Flat, located roughly 70 miles (113 kilometers) east of Phoenix.

While an environmental impact statement was issued in January 2021 during the final days of the Trump administration, the Biden administration later withdrew the report, pausing the land transfer. The US Forest Service is now expected to reissue the statement, potentially enabling the transfer to proceed by mid-June.

Rio Tinto’s growing copper push

The Resolution Copper project forms part of Rio Tinto’s broader copper expansion strategy aimed at addressing the global supply deficit.

In Mongolia, Rio Tinto’s Oyu Tolgoi mine began underground production in 2023 and is forecast to become the world’s fourth-largest copper mine by 2030. In Peru, the company has joined forces with Chile’s Codelco and Canada’s First Quantum Minerals to develop La Granja, one of the largest undeveloped copper resources globally.

Rio Tinto is also pioneering innovative extraction technologies, including its Nuton bioleaching process developed in collaboration with Arizona Sonoran Copper (TSX: ASCU), which aims to recover copper from tailings and low-grade ores with a smaller environmental footprint.