After decades of exile to environmentalism’s legal fringes, the notion that natural systems could have legal rights is receiving serious attention.

Bolivia’s Law of Mother Earth is set to pass. On Wednesday the United Nations will discuss a proposed treaty based on the Universal Declaration of the Rights of Mother Earth (.pdf), which was drafted by environmentalists last year. Both mandate legal recognition of ecosystems’ right to exist.

It’s highly unlikely that the United Nations would pass any such treaty in the foreseeable future, and the discussion has been criticized as a time-wasting...