25 CFR § 90.36
Disputes on eligibility of voters
February 24, 2021
(a) The election board shall fix a date not less than five days before the election at which time all complaints will be heard. The election board shall, at least three days before the date of election, determine any claim or challenge as to the right of any person to be listed on the roll of eligible voters.
(b) Any voter of the tribe shall have the right to challenge any person presenting himself to vote and it shall be the duty of the supervisor and a judge of the board to make such investigation then and there as they deem essential, and decide the question of whether or not a person is a listed voter.