The U.S. Justice Department has issued a legal opinion asserting that President Donald Trump has the authority to revoke national monument designations, countering a long-standing 1938 legal interpretation of the Antiquities Act.

This opinion challenges designations made by previous presidents, including two California monuments—Chuckwalla and Sáttítla Highlands—established by former President Joe Biden, which protect over 849,000 acres of culturally and environmentally significant land.

The Trump administration argues these designations obstruct energy development and that activities such as hiking and camping under Biden’s initiatives are unrelated to historical or scientific preservation.

Environmental groups and some lawmakers, notably Sen. Martin Heinrich of New Mexico, criticized the opinion, warning it undermines public land protections.

Though numerous past presidents used the Antiquities Act to safeguard key sites—with many monuments later becoming national parks—some have also scaled them back, including Trump’s controversial reductions of Utah monuments during his first term.

Legal disputes remain unresolved around these changes, as Biden reinstated protections during his presidency.

The debate centers on balancing environmental preservation against resource extraction, with strong public support cited for maintaining monument protections.