Ambiguous-Father Families

37 Pages Posted: 20 Feb 2002

See all articles by Ira Mark Ellman

Ira Mark Ellman

Center for the Study of Law and Society, Berkeley Law, University of California, Berkeley; Arizona State University College of Law; Arizona State University (ASU) - Department of Psychology

Date Written: August 17, 2001


Even though the traditional law in principle often treated biological paternity as determinative of legal paternity, in practice it did not, because biological paternity was not usually possible to determine. Regardless of the formal legal rule, the paternity presumptions established by social relations therefore usually prevailed where the social relations existed. The rule presuming that a married woman's husband was the father of her child was the most important, although not exclusive, example. In the absence of legal presumptions based upon social relations, paternity was not usually possible to establish. In the last two decades, however, scientific advances have allowed the unambiguous establishment of biological paternity in essentially all cases. The result is that the traditional focus on biological paternity can now yield new results. First, because it is now possible to learn that a child's firmly established social father is not, in fact, the child's biological father, legal paternity can be reassigned years after a child's birth. Second, biological paternity, and thus legal paternity, can be established, even years after conception and birth, for children who have had no social father. Because scientific advances make such results, once rare, now potentially common, they require the law to confront a question that it has in practice often ignored: whether legal paternity should necessarily be equated with biological paternity in such cases, here referred to as cases of ambiguous fatherhood. For marital families the question is of significant practical consequence, given the conventional estimates of professionals that approximately ten percent of children born to married mothers are not the biological children of their husband. The question also becomes important for the children born to unmarried mothers as government becomes increasingly persistent about collecting child support from the men identified as their fathers, who often have no social relationship with their biological child. This paper suggests that the formal law should be changed, where necessary, to preserve at least a portion of the pre-scientific practice, and thus the traditional alignment between social and legal paternity. It also suggests that our willingness to impose child support obligations upon biological fathers who are not social fathers is based upon policies which, when correctly understood, do not necessarily apply to all biological fathers.

Keywords: Paternity, fatherhood, child support

Suggested Citation

Ellman, Ira Mark, Ambiguous-Father Families (August 17, 2001). Available at SSRN: or

Ira Mark Ellman (Contact Author)

Center for the Study of Law and Society, Berkeley Law, University of California, Berkeley ( email )

Berkeley, CA 94720-2150
United States


Arizona State University College of Law ( email )

Box 877906
Phoenix, AZ
United States

Arizona State University (ASU) - Department of Psychology ( email )

950 S. McAllister Ave
P. O. Box 871104
Tempe, AZ 85287-1104
United States