Here. An excerpt describing the holding:

This appeal marks the latest chapter in a long-running contract dispute between the Ute Indian Tribe of the Uintah and Ouray Reservation (the Tribe) and Lynn Becker, a non-Indian. The contract concerned Becker’s work marketing and developing the Tribe’s mineral resources on the Ute reservation. Almost seven years ago, Becker sued the Tribe in Utah state court for allegedly breaching the contract by failing to pay him a percentage of certain revenue the Tribe received from its mineral holdings. Later, the Tribe filed this lawsuit, challenging the state court’s subject matter jurisdiction under federal law. The district court denied the Tribe’s motion for a preliminary injunction against the state-court proceedings, and the Tribe appeals.
We reverse and hold that the Tribe is entitled to injunctive relief. The district court’s factual findings establish that Becker’s state-court claims arose on the reservation because no substantial part of the conduct supporting them occurred elsewhere. And because the claims arose on the reservation, the state court lacks subject-matter jurisdiction absent congressional authorization.

Briefs here.