In English law, while motherhood may subsequently be transferred by adoption or the s 30 procedure, ab initio a child’s legal mother will always be the woman who gave birth to her. Although now also given statutory effect,[205] this common-law rule derives from the maxim mater est quam gestatio demonstrat (by gestation, the mother is demonstrated). Or, in the words of Lord Simon in the Ampthill Peerage case, maternity is ‘proved demonstrably by parturition’.[206] Yet we immediately have a source of confusion here. Is it gestation itself that is decisive, or does gestation merely demonstrate or offer proof that the woman who gives birth is the genetic mother of the child? So, while usually assumed to mean that legal motherhood always vests in the gestational mother, an alternative interpretation of this common-law rule could be that the test for motherhood is in fact genetic relatedness, rather than gestation. Until the development of in vitro fertilisation techniques, gestation simply constituted irrefutable evidence of the decisive genetic link.
The adoption of a universal gestational test for maternity is usually, of course, unproblematic. Its principal defect is its application to undisputed surrogacy arrangements, when the rule will vest maternal status in a woman who never intended to be the child’s mother. Because most surrogate mothers do want to hand over the baby after birth, the practical consequence of the universal gestation-based test is that the child is born into a legal limbo which will continue until parental status and responsibility are formally transferred via judicial proceedings. And, as noted earlier, since no formal transfer will ever take place in a ‘substantial proportion’ of cases, this legal limbo may continue throughout the child’s life. This sort of uncertainty, even if relatively short-lived, is clearly not in the best interests of the child. In the absence of a dispute, it would therefore seem sensible for intention to be decisive. In the handful of cases where there is a disagreement over the child’s parentage, some mechanism to resolve the dispute must be found. This could consist in a default test (gestation or intention, for example), or in some sort of ‘best interests’ assessment.
In England, depending upon the context, a variety of tests can be employed in order to identify a child’s legal father. In sharp contrast, the definition of ‘mother’ is rigidly inflexible and inattentive to the different contexts in which children are conceived. Of course, women’s gestational capacity is clearly a material difference between the sexes, and therefore adopting differential tests for motherhood and fatherhood is not presumptively discriminatory. But if we think about some of the reasons for gestational priority, a powerful argument against differential treatment of men and women emerges. Both men and women can, via gamete donation, voluntarily surrender their parental status prior to a child’s conception. But the gestational mother’s decision to relinquish her parental status will be ineffective until at least six weeks after her child’s birth.[207] The only plausible explanation for the difference is that women are assumed to be incapable of making this decision before and during pregnancy, and within the first six weeks of the child’s life. There is, in short, a danger that women might change their minds, and that their subsequent regret would be intolerable, which, according to Marjorie Shultz, reinforces ‘the sexist stereotype that women are ruled by unpredictable emotion’.[208] For men and non-pregnant women, parenthood can be acquired and transferred by clear expressions of intent on the part of the social and genetic parents. For gestating women, ‘biology is still destiny’.[209]