Mich. Comp. Laws § 780.166a: Adjudicating issue of paternity.

Sec. 16a.

The court of this state when acting as a responding court may adjudicate the issue of paternity if both of the following apply:

Paternity has not been legally acknowledged, previously adjudicated, or established by marriage.

The obligor asserts as a defense that he is not the father of the child for whom support is sought.