The common-law rule is that a married woman's husband is presumed to be the legal father of any child conceived or born during the marriage. This rule is still the starting point of legal analysis when the marriage involves an opposite-sex couple.

Actions to determine paternity may be brought under the Paternity Act. Parents may also sign an acknowledgment of parentage under the Acknowledgment of Parentage Act, and a putative father may file a notice of intent to claim paternity under the Adoption Code, which raises a rebuttable presumption of paternity. A putative father may also establish paternity under the Revocation of Paternity Act (RPA). When one or more of the parties receive Title IV-D services, actions to establish an alleged father's paternity may also be brought under the Genetic Parentage Act (GPA) or the Summary Support and Paternity Act (SSPA).

The establishment of paternity under another state's law has the same effect as a Michigan acknowledgment of parentage or order of filiation.

If a child is the subject of a petition brought in a proceeding brought under the Juvenile Code, a putative father may be entitled to notice and an opportunity to establish legal paternity. Putative fathers may not seek custody under the Child Custody Act of 1970 without a prior acknowledgment of paternity or order of filiation.

BEWARE! For a father who is not married to the mother, the mother has SOLE CUSTODY - both legal and physical - of their child until the family court orders otherwise.

In a divorce action, the court has no authority to determine the paternity of a third party, although it may determine the husband's paternity rights if the court has in personam jurisdiction over the husband. A finding of fact in a divorce decree that a child was born of the marriage bars relitigation of paternity, even if the issue was not contested.