National Farmers Union Insurance Co. v. Crow Tribe of Indians

A Crow student was injured by a motorcycle at a state-run elementary school on the Crow Reservation, and his family obtained a default judgment against the school district in Crow Tribal Court; the school district then sued in federal court to enjoin enforcement of that judgment, arguing the tribal court lacked civil jurisdiction over the non-Indian school district and invoking federal-question jurisdiction under 28 U.S.C. § 1331. The district court granted a permanent injunction, holding the tribal court lacked jurisdiction over non-Indians in civil tort matters, but the Ninth Circuit reversed for lack of federal jurisdiction, and the Supreme Court granted certiorari.