In a landmark climate trial, a Montana court on Monday ruled in favor of a group of youths who accused the western US state of violating their rights to a clean environment.

District Court Judge Kathy Seeley said a state law preventing agencies from considering the impacts of greenhouse gases when issuing permits for fossil fuel development was unconstitutional.

​The case, Held v. State of Montana – brought by 16 plaintiffs ranging in age from five to 22 – has been closely watched because it could bolster similar litigation that has been filed across the country.

​"By prohibiting analysis of GHG0 (greenhouse gas) emissions and corresponding impacts to the climate… the MEPA (Montana Environmental Policy Act) Limitation violates Youth Plaintiffs' right to a clean and healthful environment and is unconstitutional on its face," Seeley wrote.

​"Plaintiffs have a fundamental constitutional right to a clean and healthful environment, which includes climate as part of the environmental life-support system," Seeley added in her more than 100-page ruling.

Youth Plaintiffs Arrive At Court
Plaintiffs in the case arrive at court on 12 June 2023, the first day of their trial. (Robin Loznak/Our Children's Trust/AFP)

​The closely watched case was the first involving a constitutional claim against a state and also represented a rare instance in which climate experts were questioned on the witness stand.

​Julia Olson, executive director of the nonprofit Our Children's Trust, which represented the plaintiffs, welcomed the ruling as a "huge win for Montana, for youth, for democracy, and for our climate."

​"Today, for the first time in US history, a court ruled on the merits of a case that the government violated the constitutional rights of children through laws and actions that promote fossil fuels, ignore climate change, and disproportionately imperil young people," Olson said.

​"As fires rage in the West, fueled by fossil fuel pollution, today's ruling in Montana is a game-changer that marks a turning point in this generation's efforts to save the planet from the devastating effects of human-caused climate chaos," she said in a statement.

'Dystopian movie'

Emily Flower, spokeswoman for Montana attorney general Austin Knudsen, denounced the ruling and said the state would appeal.

​"This ruling is absurd, but not surprising from a judge who let the plaintiffs' attorneys put on a weeklong taxpayer-funded publicity stunt," Flower said.

​"Montanans can't be blamed for changing the climate — even the plaintiffs' expert witnesses agreed that our state has no impact on the global climate," she added.

​At the heart of the case was a provision within fossil fuel-friendly Montana's constitution that says: "The state and each person shall maintain and improve a clean and healthful environment in Montana for present and future generations."

​The youths said they had been harmed by the "dangerous impacts of fossil fuels and the climate crisis," with children "uniquely vulnerable" to its worsening impacts.

​During closing arguments, Nate Bellinger of Our Children's Trust said his clients were asking the state government to "embrace its constitutional responsibility to alleviate the harms of its own conduct."

​"The plaintiffs acknowledge that the work to stop and reverse climate change will be a lifetime journey, but they are asking this court for help," he said.

​Montana assistant attorney general Michael Russell on the other hand argued that energy policy should be decided by the people through their elected representatives.

​Russell said that while the state accepted that man-made emissions were responsible for warming, expert witnesses had not been able to quantify the extent to which Montana's laws were responsible.

​The trial began on June 12 and concluded a few days earlier than expected after Montana declined to call to the stand several experts, including its only climate scientist, Judith Curry.

​Over the course of the proceedings, the court heard testimony from the plaintiffs about ways their health, emotional wellbeing, family finances and cultural traditions had been affected.

​Lead plaintiff Rikki Held, 22, whose family runs a ranch in Montana, said that their livelihoods and quality of life had been increasingly impacted by wildfires, extreme temperatures and drought.

​Claire Vlases, 20, said: "When I think about summer, I think about smoke. It sounds like a dystopian movie, but it's real life."

© Agence France-Presse