Source: Benatar, David. Better Never to Have Been (2008 1 edn). pp. 104-105.
It is widely thought that these considerations are sufficient to justify a legal right to have children. However, those who think that there ought to be a legal right to have children but also accept the conclusion that it is always a harm to come into existence face the following difficulty. A legal right to have children is not an absolute entitlement but instead a very strong presumption in favour of having children. It is in the nature of a presumption that it can be defeated. Thus one defender of a right to procreative freedom notes that ‘those who would limit procreative choice have the burden of showing that the reproductive actions at issue would create such substantial harm that they could justifiably be limited.’⁹
⁹ Robertson, John, Children of Choice (Princeton: Princeton University Press, 1994) 24.
This is not very controversial. However, if one thinks that coming into existence is always a great harm, then the presumption in favour of a right to procreate is always defeated. But a right that is always defeated is not really a right. Although it might still be argued that it is a right in principle—a presumption that has to be defeated, even though it always is defeated—such rights are not suitably enshrined in law. To make the case that people ought to have a legal right to have children, one must surely demonstrate that there should be a presumption in practice, and not merely in principle, to choose whether to have children. The problem, then, is that a defeasible legal right to have children is not a plausible candidate for a legal right if the defeasibility conditions are always met.
The emboldened sentence feels wrong to me, as legal (e.g. constitutional) rights have remained legal, notwithstanding their being violated by humans daily.