25 CFR 11.500: Law applicable to civil actions.

(a) In all civil cases, the Magistrate of a Court of Indian Offenses shall have discretion to apply:

(1) Any laws of the United States that may be applicable;

(2) Any authorized regulations contained in the Code of Federal Regulations; and

(3) Any laws or customs of the tribe occupying the area of Indian country over which the court has jurisdiction that are not prohibited by Federal laws.

(b) The delineation in paragraph (a) of this section does not establish a hierarchy relative to the applicability of specific law in specific cases.

(c) Where any doubt arises as to the customs of the tribe, the court may request the advice of counselors familiar with those customs.

(d) Any matters that are not covered by the laws or customs of the tribe, or by applicable Federal laws and regulations, may be decided by the Court of Indian Offenses according to the laws of the State in which the matter in dispute lies.