Believe it or not, the biological father of the child does not have the constitutional right to establish paternity of a child born to the wife of another man. Dawn D. v Superior Court (1998) 17 C4th 932, 944.
The husband of a woman who conceives as a result of an extramarital affair is presumed to be the child’s legal father. Rodney F. v Karen M. (1998) 61 CA4th 233, 239. Lisa I. v Superior Court (Phillip V.) (2005) 133 CA4th 605, 622.
Both the California Supreme Court and the United States Supreme Court have rejected due process challenges to the presumption under the law, that a child born during marriage is the presumed child of the husband. Michael H. v Gerald D. (1989) 491 US 110, 109 S Ct 2333; Michelle W. v Ronald W. (1985) 39 C3d 354.
Additionally, equal protection challenges have been unsuccessful in the California Supreme Court. The court held the state has a legitimate interest in preferring a man who has undertaken the responsibilities of marriage and family, over a man who has merely biological ties to a child. Michelle W. v Ronald W. (1985) 39 C3d 354, 363; Rodney F. v Karen M. (1998) 61 CA4th 233, 239.
However, a biological father may have some rights if a married couple allows a parental relationship to develop between the child and biological father. Dawn D. v Superior Court (1998) 17 C4th 932, 944. Thus, there may be certain policy and logic arguments which may be used to argue paternity.
Michael H. left open the possibility that the presumption of paternity to the husband of a child born during marriage might be unconstitutional if applied to substantially different facts. Therefore, it still within the realm of possibility to establish parental rights.