The case is captioned In re Estate of Big Spring (Mont. S. Ct.). Here is the brief: Blackfeet Amicus Brief.

An excerpt from the brief:

This case comes before this Court on the appeal of the Appellants from the decision of the Ninth Judicial District of Glacier County which ruled against a Motion to Dismiss by the Appellants based on the lack of subject matter jurisdiction over the estate of William Big Spring, II, an enrolled member of the Blackfeet Tribe, who, at the time of his death was a resident of the Blackfeet Reservation and whose estate consisted of both trust and fee land solely within the exterior boundaries of the Blackfeet Reservation. The District Court stated that there was concurrent jurisdiction over this property and that the District Court was therefore the proper forum for the probate of this Indian-owned fee land.

Appellants argue that the State District Court is without jurisdiction over the probates of resident enrolled members of the Blackfeet Tribe. Appellants further state that the probate of the trust land of such persons is vested in the Administrative Courts of the United States and that the probate of the fee land is vested, exclusively in the Blackfeet Tribal Court. That is also the view of the Blackfeet Tribe as seen in this Amicus Brief.