A group of young people who sued the state of Montana for violating their right to a clean environment can claim a big victory today.

A state court ruled in their favor, finding that the plaintiffs “have experienced past and ongoing injuries resulting from the State’s failure to consider [greenhouse gases] and climate change, including injuries to their physical and mental health, homes and property, recreational, spiritual, and aesthetic interests, tribal and cultural traditions, economic security, and happiness.”

Montana’s constitution includes rights to a “clean and healthful environment” for residents and “future generations.” The plaintiffs sought to force the state to drop a provision in the Montana Environmental Policy Act that barred officials from considering the consequences of climate change when permitting new energy projects, saying it violated those constitutional rights.

Now, the state may have to rethink that provision. The decision today says that “the State must either: 1) have discretion to deny permits for fossil fuel activities when the activities would result in GHG emissions that cause unconstitutional degradation and depletion of Montana’s environment and natural resources, or infringement of the constitutional rights of Montana’s children and youth; or 2) the permitting statutes themselves must be unconstitutional.”

The judge’s decision, however, is likely to face legal challenges that would send the case to the Supreme Court of Montana. If that happens, plaintiffs would face a lengthy legal battle before winning any concrete policy changes.

If Held and the other plaintiffs are successful, the Montana case could signal a shift for similar climate suits that have been filed by youth plaintiffs in all 50 states. Four of those suits outside of Montana are still pending, including a case filed against Hawaii’s Department of Transportation that’s expected to go to trial next year.