@Sheril The important unstated context is that the language they're citing from Montana's consitution that is core to its case, comes from the state rewriting itself a new consitition in 1972 -- the fifth-newest among the states -- and a successful push by environmental activists to get the language included.
https://montanafreepress.org/2020/09/22/shared-state-episode-4-the-quiet-beauty-of-our-state/
(30m)
"""
Nearly 50 years ago, a group of Montanans pushed for strong environmental protections and the right to “a clean and healthful environment.” What they created was groundbreaking. Only about a half-dozen other states recognize environmental rights in their constitutions, and Montana is the only state that calls that right “inalienable.”
...
"""
(Montana's public journalism scene has consistently been absolutely TOP-TIER in work I keep seeing them output, highly recommend.)