Rikki Held

Young people have spent their entire lives surrounded by the effects of climate change. That’s why Rikki Held stepped forward to become the lead plaintiff in a lawsuit brought by Our Children’s Trust—a not-for-profit law firm that specializes in environmental cases—suing the state of Montana for violating its own constitutional guarantee that it would provide citizens “a clean and healthful environment.” The case, Held v. State of Montana, was the first constitutional and the first youth-led climate lawsuit to go to trial in the U.S., and it resulted in a historic ruling—one that could provide a road map for similar efforts. On Aug. 14, the Montana District Court sided with Held and her fellow young plaintiffs, ages 5 to Held’s 22. It is now up to Montana’s legislature to bring its laws in line with the state constitution. With the trial over, Held plans to pursue a graduate degree in climate or hydrology—and to continue her green activism going forward.

Write to Jeffrey Kluger at jeffrey.kluger@time.com.