Mich. Comp. Laws § 168.748
After issue joined in any case of contested election, either party to the cause may present a petition to the court before which the said cause is to be tried, setting forth among other things that the petitioner has good reason to believe and does believe that 1 or more voters at the election out of which the cause has arisen, naming him or them, and stating his or their place of residence, were unqualified to vote at such election; that he believes the same can be established by competent testimony; that the ballot or ballots of such voter or voters were received after being challenged, as provided by law; and praying that the court may try and determine the question of the qualification of such voter or voters at said election, which petition shall be verified by the oath of the petitioner or some other person acquainted with the facts, and thereupon the court shall direct an issue to be framed, within a time to be fixed therefor, for the purpose of determining the question of the qualifications of the voter or voters named in said petition to vote at said election; and such issue shall stand for trial as in other cases, and the verdict of the jury or judgment of the court upon such issue so made shall be received, upon the trial of the principal issue in said cause, as conclusive evidence to establish or to disprove the said qualifications of said voter or voters.
MCL 168.748