ANCHORAGE, Alaska— The Center for Biological Diversity and Sovereign Iñupiat for a Living Arctic sent a notice today of their intent to sue the federal government for granting Hilcorp Alaska LLC an extension for expired oil and gas drilling leases in the Arctic Ocean. The leases are for the proposed Liberty Unit project, which would be in federal waters.

The Biden administration denied Hilcorp’s lease extension request in December 2024 and the leases expired. In November 2025 the Trump administration reversed the denial under the pretense of a national energy emergency.

“This rollback is clearly not lawful and I’m deeply concerned about the harms this drilling project would cause to the Arctic Ocean’s sensitive marine ecosystem,” said Rebecca Noblin, Alaska senior attorney at the Center for Biological Diversity. “The only real emergency is the threat to bowhead whales, walrus and polar bears from Trump’s push for oil drilling in the Beaufort Sea. These leases were ended fair and square and it’s time to focus on protecting the precious Arctic rather than plundering it for short-term profits.”

Today’s notice to the Interior Department and the Bureau of Safety and Environmental Enforcement says construction noise and other drilling activities could disturb the habitat of numerous vulnerable Arctic animals, including bowhead whales, walrus, ice seals and polar bears. An oil spill in the Arctic Ocean would be all but impossible to contain and clean up, especially because sea ice is present much of the year.

BP acquired the oldest Liberty Unit lease in a 1991 sale. The Liberty leases were previously extended 11 times. Hilcorp acquired primary ownership and operatorship of the Liberty project from BP in 2014.

In 2018 the first Trump administration approved Hilcorp’s plan to drill at the Liberty Unit. The Center and other environmental groups sued over the approval because it failed to adequately consider the project’s climate impacts and harm to polar bears. The groups won their lawsuit in 2020, with the court vacating the project’s approval.

In December 2024 the Interior Department denied Hilcorp’s request for a one-year lease extension because the company failed to meet regulatory requirements, including failing to provide a revised and completed drilling plan nearly four years after the court deemed the previous plan unlawful. The company also failed to provide an adequate oil spill response plan. Because the Liberty leases are all past their initial 10-year terms, without an extension, the leases automatically expired.

Hilcorp appealed the denial in February 2025, but in May the Trump administration rescinded the denial and the appeal was dismissed. In November the Trump administration granted Hilcorp a five-year lease extension, through 2029.

Liberty would be the first oil extraction project fully within federal waters in the Arctic Ocean. Hilcorp owns the three leases that make up the Liberty Unit. To reach the Liberty leases, Hilcorp plans to drill horizontally from an existing artificial gravel island that is part of the Endicott project in state waters.

The Outer Continental Lands Act requires that parties submit a 60-day notice of intent to sue before a lawsuit can be filed. The Center and Sovereign Iñupiat for a Living Arctic intend to file their formal lawsuit in March.