Dateline Resources (ASX:DTR) said its wholly owned subsidiary, Colosseum Rare Metals, has filed a motion to intervene as a defendant in a US federal lawsuit challenging the federal government's April 2025 recognition of the company's valid existing rights at the Colosseum Mine in California, according to a Friday Australian bourse filing.

The case was brought by the National Parks Conservation Association against the US Department of the Interior and the National Park Service, per the filing.

The company states in its filed materials that agency correspondence from April 2025 affirmed its valid existing rights, confirmed that its Bureau of Land Management-approved plan of operations remains in force without requiring further approval, and withdrew a previously issued damages demand, the filing said.

The company notes that the motion to intervene is a procedural step that, if granted, would allow the company to participate directly in the case, the filing added.

The company's shares rose 4% in recent Friday trade.