Peter Stanley appealed the decision, as the state had never provided him a hearing to determine whether he was a fit parent, which would have occurred for a married father under similar circumstances.

Mr. Stanley claimed that his lack of hearing violated (1) his Fourteenth Amendment right of equal protection and (2) Due Process.

The Court also held that Illinois' denial of unwed fathers a hearing and extending it to all other parents (wed fathers, both wed and unwed mothers) violated the equal protection of the laws guaranteed by the Fourteenth Amendment.

They also argued, "I believe that a State is fully justified in concluding, on the basis of common human experience, that the biological role of the mother in carrying and nursing an infant creates stronger bonds between her and the child than the bonds resulting from the male's often casual encounter."

He essentially argued in favor of the tender years doctrine, which had already begun being eliminated from state statutes that determined custody after divorce.