Gerald D. (defendant) and Carole D. were married in 1976 in Las Vegas and resided together in California. In 1978, Carole became involved in an adulterous affair with a neighbor, Michael H. (plaintiff). In 1980, she conceived a child, Victoria. Soon after delivery, Carole informed Gerald that Michael might actually be the father of Victoria, at which point Michael and Carole each took DNA tests showing that there was a 98.7% chance that Michael was Victoria’s father. Soon after, Gerald and Carole separated, and Carole took up residence with a third man and rebuffed Michael’s attempts to visit Victoria, who he strongly believed to be his daughter. Although Michael filed an action in California Superior Court to establish his paternity and grant him visitation rights, the case was withdrawn after Carole started seeing Michael again and signed an agreement stipulating that Victoria was their daughter. Carole later reconciled with Gerald and went to live with him again with Victoria. In 1984, however, Michael and Victoria, through her guardian ad litem brought another action to establish paternity and visitation rights for Michael. Gerald intervened and moved for summary judgment on the ground that under California law, there were no triable issues of fact regarding Victoria’s paternity as California law provided that “the issue of a wife cohabitating with her husband, who is not impotent or sterile, is conclusively presumed to be a child of the marriage.” Later in 1985, the California Superior Court granted Gerald’s motion for summary judgment and rejected Michael and Victoria’s motions for continued visitation. Michael claimed that the law at issue denied him an opportunity to establish his paternity and violated his Fourteenth Amendment due process rights. A California court of appeals upheld the constitutionality of the California law, and Michael appealed to the United States Supreme Court.