Mich. Comp. Laws § 168.747
In case of a contested election, on the trial thereof before any court of competent jurisdiction, it shall be competent for either party to the cause to have produced in court the ballot boxes, ballots and poll books used at the election out of which the cause has arisen, and to introduce evidence proving or tending to prove that any person named on such poll lists was an unqualified voter at the election aforesaid, and that the ballot of such person was received. On such trial, the correspondence of the number endorsed on a ballot as herein provided with the number of the ballot placed opposite the name of any person on the poll lists shall be received as prima facie proof that such ballot was cast by such person: Provided, That the ballot of no person shall be inspected or identified under the provisions of this chapter unless such person shall consent thereto in writing, or unless such person has been convicted of falsely swearing in such ballot, or unless the fact that such person was an unqualified elector at the time of casting such ballot has been determined.
MCL 168.747