When will a tribal court have jurisdiction to adjudicate a claim brought by a non-tribe?

When, as in this case, it is plain that no federal grant provides for tribal governance of nonmembers' conduct ... covered by [Montana v. United States,' 450 U.S. 544, 101 S.Ct. 1245, 67 L.Ed.2d 493 (1981) ] main rule, it will be equally evident that tribal courts lack adjudicatory authority over disputes arising from such conduct. As in criminal proceedings, state or federal courts will be the only forums competent to adjudicate those claims. Therefore, when tribal-court jurisdiction over an action such as this one is challenged in federal court, the otherwise applicable exhaustion requirement, must give way, for it would serve no purpose other than delay.