In Adoption of Kelsey S. (1992) 1 Cal.4th 816, during the mother's pregnancy the biological father objected to her plan to place the child for adoption. Two days after the child's birth, the biological father filed an action to establish his parental relationship in order to block the adoption. (Id. at pp. 821-822.) The father succeeded in obtaining supervised visitation of the child pending resolution of the dispute, and the parties stipulated that he was the biological father. However, the trial court ruled that he was not a presumed father, and ultimately concluded that the best interests of the child required termination of his parental rights so as to allow the adoption to proceed. (Id. at pp. 822-823.) Reversing the lower court's ruling, our Supreme Court held that if "an unwed father promptly comes forward and demonstrates a full commitment to his parental responsibilities- emotional, financial, and otherwise-his federal constitutional right to due process prohibits a termination of his parental relationship absent a showing of his unfitness as a parent." (Id. at p. 849.) The court explained the level of commitment that must be shown in order to warrant this constitutional protection: "The father's conduct both before and after the child's birth must be considered. Once the father knows or reasonably should know of the pregnancy, he must promptly attempt to assume his parental responsibilities as fully as the mother will allow and his circumstances permit. In particular, the father must demonstrate 'a willingness to assume full custody of the child-not merely to block adoption by others.' A court should also consider the father's public acknowledgment of paternity, payment of pregnancy and birth expenses commensurate with his ability to do so, and prompt legal action to seek custody of the child." (Id. at p. 849.) Because the facts were not sufficiently developed to determine whether the father in Kelsey S. had demonstrated a sufficient commitment to his parental responsibilities, the Supreme Court remanded the matter for further hearing. (Id. at pp. 850-851.)