The most significant feature in Jewish law is its methodological consistency for dealing with questions of maternity, paternity, and parental status. Jewish law focuses on immutable relationships, easily ascertainable and without any subjective elements of court judgment. Paternity is irrevocably established by being the biological and genetic father. Even in the relatively difficult case of artificial insemination, Jewish law looks to objective criteria, even if there is a dispute over which objective criteria should control. Jewish law does not accept the American approach of looking at various fact-specific equities, such as estoppel between the litigants, or consent to various actions, or the presence of an adopted child whose custodial situation is apparently not in harmony with the legal parental situation.
Jewish law fixes on unchangeable paternity established at birth.
The same can be noted about maternal relationships. Jewish law immutably establishes that the natural parent is the mother. In the case of surrogate motherhood, motherhood is fixed by determining when conception occurred, and where that is not legally dispositive, as in test tube conception, where birth occurs, nonetheless Jewish law bases its establishment of motherhood on objective, rather than subjective, criteria. American law has historically rejected these criteria and maintains that parenthood can be totally transferred by the courts, and that the equities of each and every situation require a different result. This is true in the establishment of both maternal and paternal relationships.