The U.S. Supreme Court on Friday agreed to review a decision that revived a long-running lawsuit by the Navajo Nation, which claims that the U.S. Interior Department has a duty to develop plans to provide the reservation with an adequate water supply.

The high court granted two petitions for certiorari – one by the federal government, one by Arizona and other states -- challenging last year’s decision by a three-judge panel of the 9th U.S. Circuit Court of Appeals.

The 9th Circuit said “an irreversible and dramatically important trust duty” was implied by 175 years’ worth of treaties and court decisions. The challengers, however, say implied rights are unenforceable.

“The federal treaties with the Navajo Nation…do not address water at all,” and the doctrine of implied water rights “cannot justify imposing such a fiduciary duty,” lead counsel Rita Pearson Maguire argued in the states’ cert petition.