Law professor Sherry Colb, a former law clerk to Justice Blackmun and a vocal supporter of abortion rights, opens her blog post titled “In Defense of Viability” by offering these cogent criticisms of a regime that would make viability the line between permitted and prohibited abortions:
Viability … would appear to have little to recommend it as a border between prohibiting and permitting abortion. What changes when a fetus becomes viable outside the womb? What changes is more or less that the fetus’s lungs have developed enough to take in oxygen without the placenta to absorb it from the mother’s bloodstream and pass it along through the umbilical cord. Is the ability to breathe outside the womb a morally relevant characteristic? How could it be? The ability to breathe is essential for life, but it is not the sort of thing to which we attach moral status, any more than the ability to see or to walk or to speak are such abilities. Such capacities are morally neutral, at best. At worst, a fixation upon them as a prerequisite for rights appears to embrace a problematic ableism. Are people who cannot breathe without assistance somehow “less than” those who can?
In addition to its irrelevance (and possible perversity) as a criterion for a fetus’s moral standing, viability also seems a bit illogical. Indeed, one might say that waiting until viability to protect the right to abortion is exactly backward. Up until viability, the fetus needs the mother’s body in order to live, yet we give the mother the right to remove the fetus from her body during that period and thus the right to kill it. But then, at the moment when the fetus can survive without having to live inside its mother’s body, it is then that, by permitting an abortion ban, we say that it is okay to require the mother to keep the fetus inside her body for another 15 weeks or so. She can take the fetus out when it needs to be in but once it can survive an exit, it must stay in. What kind of a rule is that? It is like providing that the warden of a prison, in case of a fire, must keep all prisoners locked in the burning building. But then, once the fire is extinguished, the warden must liberate the prisoners.
(Colb goes on to argue that the viability line nonetheless “has something going for it, though not anything that the Court has identified”—namely, that from viability on, a woman can terminate her pregnancy by removing her “unwanted human parasite” without necessarily killing it in the process.)