LIVINGSTON, MONTANA — Eva Lighthiser, a 20-year-old climate activist from Livingston, Montana, is preparing testimony for the Ninth Circuit Court of Appeals in Lighthiser v. Trump, a federal lawsuit challenging executive orders that expanded fossil fuel development. The Ninth Circuit, which covers Montana, will decide in the coming months whether to reinstate the case after a lower court dismissed it in the fall.

Lighthiser and 22 other young Americans filed the suit accusing the federal government of violating their constitutional rights by passing executive orders boosting planet-warming fossil fuels. In April, Lighthiser and her co-plaintiffs traveled to Portland, Oregon, to push for reinstatement of the case.

"We are challenging this administration for sacrificing the lives of myself and my fellow plaintiffs by expanding fossil fuels for the sake of power," Lighthiser said. Describing the Portland appearance, she said, "It was a nerve-racking, but invigorating experience."

In May 2025, one of Lighthiser's lawyers asked her if she wanted to be the lead plaintiff in the federal case, a role that would include mentoring younger challengers. "That was really a moment when it clicked. My name against his name," Lighthiser said.

The federal case follows years of climate litigation by Lighthiser. On her 14th birthday, she filed Held v. Montana, alleging that the state's pro-fossil fuel policies violated the state constitution's guarantee of a right to a clean and healthful environment for present and future generations. In 2023, the case became the first lawsuit of its kind to go to trial, and a judge ruled in favor of the plaintiffs. State lawmakers have since enacted new laws that contradict the ruling and that the plaintiffs say should be overturned.

Our Children's Trust, a non-profit law firm involved in dozens of legal actions against governments across the United States, has worked with Lighthiser on the litigation. In early 2025, Lighthiser spoke at an event with Julia Olson, the group's founder.

"It became clear early in the second Trump administration that a federal case was something to pursue. Eva was actually one of the first youth who we were in conversation with and who wanted to be involved," Olson said.

Lighthiser grew up camping and climbing mountains in Livingston, where mile-long coal trains pass blocks from her family's home. In 2018, the Shields River flooded and washed out the bridge the family used to reach Livingston, forcing a 30-minute detour each day. In 2022, the Yellowstone River overflowed, inundating homes, turning streets into streams, and causing $128 million in damages, with community members organizing cleanup efforts afterward. A climate-linked parasite killed tens of thousands of fish in the Yellowstone River in 2016, closing parts of the river.

An April poll found that 90% of Montanans, including 82% of Republicans, said conservation issues were important when deciding whether to support an elected official. In early 2020, Lighthiser began hearing about youth-led climate litigation.