Though many states recognize the legal rights of biological fathers, the law overwhelmingly favors married fathers. In some states, an unmarried man who conceives a child with a married woman may find it impossible to establish any rights over the child unless he is listed on the birth certificate. Generally, the amount of legal rights the biological father can claim depends on what kind of a relationship he has with the child.
Putative Father Registry
A putative father is a man who is presumed to be the biological father of a child born to an unmarried woman. Some states have established a putative father registry, in which a man can voluntarily acknowledge his paternity. By supplying his name, the name of the biological mother and the name of the child to the registry, the biological father will be able to obtain rights over the biological child. These rights are typically limited to notification rights, and ensure that the father will be told if there are any court proceedings initiated to terminate parental rights or begin an adoption. This notification will permit the biological father to appear in court to contest the action.
Constitution
The U.S. Supreme Court has acknowledged that biological fathers are permitted rights to their children only if the father has formed a substantial relationship with the child. The meaning of the term "substantial relationship" is open for individual states to determine. Typically, a substantial relationship exists when a father has supported the child both financially and emotionally during its upbringing. Whether or not a substantial relationship has been formed will be determined on a case-by-case basis by the state family court.
Establishing Paternity
If the biological father is not named on the child's birth certificate, and the mother is wed to a man who claims parental rights over the child, the biological father can only establish paternity through court order. Every state court is different as to how this filing must take place, but there tends to be a large presumption that the husband of the birth mother is the biological father. If the biological father successfully establishes his paternity, he may petition the court for custody or visitation. This determination is made on a case-by-case basis, and it tends to be very difficult for a biological father to win custody over the married mother.
Termination
A biological father has the legal right to terminate his parental rights. This may only be done with the consent of the mother. Termination of rights does not excuse the biological father from child support obligations unless the mother is married or marries, or the child is adopted. A biological father who terminates his rights may later attempt to reestablish a legal relationship with the child; however, courts are very unlikely to grant these rights unless there is a substantial reason.


