I'm not sure that's very useful, as it deals with the Feds imposing an affirmative duty onto the states. But SCOTUS did say that one of the three provisions exceeded the power of FedGov over states, and severed that provision from the federally imposed nuclear waste disposal regime. IOW, the case is sort of a mixed bag.
No wonder it confused me. It was cited by another FReeper as a landmark fed gov vs states rights case.
NOW, I am going to do my laundry!