In Armstrong, the divorced mother had custody of the child, while the father was ordered to pay child support. The mother remarried. Two years later, the new husband petitioned to adopt the child. The mother provided evidence that the father had not paid child support during those two years. Although the mother knew the father's location, the juvenile judge ordered the adoption without notice to him.

The father later learned of the adoption and moved to annul it. The court held a hearing in which the father introduced evidence trying to show that he had paid child support. The court denied the motion to annul. The father appealed, arguing that the lack of notice had violated his due process rights. The Texas Appellate Court upheld the denial, and the Texas Supreme Court declined to review the case.

The U.S. Supreme Court held that the lack of notice violated the father's due process right. Moreover, the later hearing after the motion to annul did not suffice because the burden of proof had shifted. Had the father received timely notice, the mother would have had the burden to show failure to support. Instead, the natural father had the burden of overcoming an adverse judgment. Only by vacating the order and holding a new hearing could due process be achieved.

Stanley v. Illinois, 405 U.S. 645 (1972) (unwed fathers)

This case established the rule that an unwed father who has a developed relationship with his child is entitled to a hearing on his parental fitness before the state may take custody of his child.

In Stanley, the unwed father lived intermittently with the mother for 18 years. They had three children when the mother died. Illinois law made children of unwed mothers state charges in that situation. A father could petition for custody, adoption, or guardianship. Divorced, widowed, and separated fathers, however, were not deprived of their children absent proof of unfitness, which the state had the burden to show. The state's interest was to protect the mental and physical welfare of children and the community, and to strengthen the child's family ties whenever possible, removing him from his parents only where the child's welfare or public safety required it.

The Illinois law violated equal protection because removing children from an unwed parent who had a relationship with his child did not further the state's interest any more than removing a child from a married father would further the state's interest. Thus, a hearing was required to determine fitness. Letting the father petition to adopt the children did not give equal protection because the law gave the father no priority in the adoption and wrongly put the burden on him to show that he was the most suitable of all those who might want custody of the children.