A growing number of states have banned abortion after twenty weeks on the grounds that the fetus at that stage experiences pain. Such laws run contrary to current abortion law, and so are almost certain to be challenged in court. In Roe v. Wade the Supreme Court said that the constitutional right to abortion extends until the fetus is viable, between twenty-four and twenty-eight weeks. After viability, states may ban abortion entirely except where continuing the pregnancy would threaten the woman’s life or health. The viability threshold was upheld in Planned Parenthood v. Casey.
Why viability? The Roe court said that this is “the ‘compelling’ point . . . because the fetus then presumably has the capability of meaningful life outside the mother’s womb.” Some commentators point out that this is no justification; the capacity for independent life does not explain the significance of viability. It merely gives the meaning.
Another problem with viability is that it seems to depend on medical technology. What if fetuses under twenty-three weeks could be placed in an artificial uterus and brought to development there? Would we then say that even a first-trimester fetus was viable? This focuses on one aspect of viability only—namely, the capacity for independent existence. Another aspect is development. The justification for viability is that a fetus of twenty-four to twenty-eight weeks is so substantially developed, so similar to a newborn, that it has a claim to societal protection—so long as this does not threaten the pregnant woman’s life or health. Any attempt to ban abortions much earlier in pregnancy—as in a bill passed by the Ohio state legislature in June that would ban abortion after a fetal heartbeat is detectable, which can occur as early as six weeks—would be so restrictive as to vitiate the right to abortion altogether.
It could be argued that sentience is a more rational threshold than viability because of the connection between sentience and moral considerability. If, as many experts believe, sentience and viability occur around the same time, then from a practical standpoint, it does not matter whether sentience or viability is chosen. But if sentience is the standard, and if it occurs earlier than viability, then abortion rights are restricted. Thus, much of the debate has turned on when fetal sentience occurs. Some are adamant that fetal sentience prior to twenty-four weeks is impossible, but other researchers do not rule it out. The development of neural networks necessary for the experience of pain might be present as early as seventeen weeks.
Opposition to these laws should not be based on when sentience occurs, since this might change with more evidence. All we can say now is that the fetus almost certainly cannot feel pain during the first trimester and almost certainly can during the third. The exact onset of sentience in the second trimester is not just unknown; it may even be unknowable. It depends on the development of neural connections, which is a process, not an event. Drawing any exact line within a process is likely to be arbitrary.
The choice between sentience and viability to justify the prohibition of late abortions is not the real issue. What really matters—and what pro-choice advocates should stress—is that late abortions are not denied to women who need them to preserve their own lives or health. Roe makes this clear, and subsequent cases have affirmed it.
That is what is so upsetting about the story of Danielle Deaver. Deaver was at twenty-two weeks in a wanted pregnancy when her water broke, and the amniotic fluid did not rebuild. Her doctors said that fetal development had stopped and that the fetus stood only a remote chance of being born alive. Deaver also faced a risk of serious infection. She and her husband opted for inducing labor. But because inducing labor, if not done to save the life of the fetus, is legally defined as abortion, and Nebraska law prohibits abortion after twenty weeks, doctors and hospital lawyers concluded that the procedure would be illegal.
After ten days, Deaver went into labor...