Montana’s Supreme Court on Wednesday upheld a landmark climate ruling that said the state was violating residents’ constitutional right to a clean environment by permitting oil, gas and coal projects without regard for global warming.

The Montana Supreme Court on Wednesday upheld a district court ruling in the nation’s first constitutional climate change trial, affirming that the youth plaintiffs have a “fundamental constitutional right to a clean and healthful environment” while revoking two Montana statutes.

The 6-1 ruling is a major, rare victory for climate activists, who have tried to use the courts to force action on activities they say are harming the planet.