When the U.S. Supreme Court justices agreed to hear arguments over Mississippi’s 15-week abortion ban in a case known as Dobbs v. Jackson Women’s Health Organization, they focused on a single question: whether “fetal viability” is a legitimate criteria for how far states may go to restrict women’s access to abortion.

In the 1973 decision in Roe v. Wade, the court majority held that a women’s right to choose to end a pregnancy was protected by the Constitution, but that states could limit that right after the second trimester or 28 weeks, when the fetus might survive outside the womb. In the 1992 ruling, Planned Parenthood v. Casey, the court affirmed that right, but opted for a framework based on fetal viability rather than trimesters. Here’s why that’s important and what that means for the case currently before the court, and more broadly, for abortion rights in the United States.

What is fetal viability?

In medicine, it’s the point at which the fetus can survive outside the womb. It is generally considered to be around 23 to 24 weeks, but there’s no universal consensus and some hospitals will resuscitate and actively treat babies born in the 22nd week of pregnancy. There are rare cases in which babies born at 21 weeks have survived.

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Justice Harry Blackmun, writing the majority opinion for Roe v. Wade, defined viability as the point where a fetus “has the capability of meaningful life outside the mother’s womb”:

With respect to the State’s important and legitimate interest in potential life, the “compelling” point is at viability. This is so because the fetus then presumably has the capability of meaningful life outside the mother’s womb. State regulation protective of fetal life after viability thus has both logical and biological justifications. If the State is interested in protecting fetal life after viability, it may go so far as to proscribe abortion during that period, except when it is necessary to preserve the life or health of the mother.


How has viability changed over the past 50 years?

In 1973, babies born at 28 weeks of pregnancy were thought to have little chance of survival. In the following decades, however, that timeline compressed by about one week every 10 years, thanks to medical advances and better understanding of treatments. These include the administration of steroids to the mother before a premature delivery to help with a baby’s lung development, and new instruments for performing delicate surgery on tiny babies.

Many of our current state and medical standards use 23 to 24 weeks as the standard for viability, but several groundbreaking studies published in the past few years have challenged that view and argued that it should be 22 weeks. As a result, a growing number of institutions are offering aggressive treatment to babies at that gestational age.

The youngest premature baby to survive is believed to be Curtis Means, born in July 2020 at 21 weeks-and-one-day and weighing 14.8 ounces, in Alabama.

Is viability a legitimate scientific metric?

While it is not a fixed number, the concept underlies many ethical and legal standards for medical care. For example, this fall the American College of Obstetricians and Gynecologists updated its guidelines to allow doctors to consider giving steroids to the mother at 22 weeks if premature birth appears likely. That was in apparent recognition of recent studies that babies born around that time may be potentially viable by surviving outside the womb. Children born at very premature gestational ages, however, are still more likely to have lifelong challenges from asthma to cerebral palsy.

What does viability have to do with Mississippi’s abortion law?

In 2018, the Republican-dominated Legislature in Mississippi passed a law banning abortion if “the probable gestational age of the unborn human” was determined to be more than 15 weeks. The statute included narrow exceptions for medical emergencies or “a severe fetal abnormality.” But the measure has never gone into effect. That’s because lower courts have ruled it violates the Supreme Court’s decision in Roe affirming a woman’s constitutional right to terminate her pregnancy up until the point of viability.

That gets at the heart of Wednesday’s case — whether the high court’s new conservative majority will overturn fetal viability as a legal criteria, or perhaps compress the timeline still further. The question the justices agreed to hear last May when they decided to take up the Mississippi case was this: “Whether all pre-viability prohibitions on elective abortion are unconstitutional.” In the years since the court’s ruling on Roe, lower courts have struck down many abortion bans — some as early as after six weeks of pregnancy. Earlier this year, however, the high court let stand a Texas law barring the procedure after six weeks due to its unique enforcement, where private individuals are charged with enforcing it.


What are some arguments for and against keeping the viability framework?

Abortion rights groups such as Planned Parenthood and the Abortion Care Network say overruling Roe “would cause grave harm,” and lay out reasons why some people are unable to obtain an abortion earlier than 15 weeks in an amicus brief. They say some of those seeking second-trimester abortions don’t realize they are pregnant earlier. They also note that those seeking the procedure later are often low-income and people of color who must overcome barriers to getting to a health center, such as a lack of transportation. Health centers offering abortion can be few and far between in some states.

Some reproductive rights experts argue further that viability is the point at which a woman’s interests can be separated from that of a fetus. “Before viability, that there is no way for the pregnant woman to defend herself against an unwanted pregnancy without also ending her embryo’s or fetus’s life,” Sherry F. Colb, a Cornell law professor wrote in a recent blog post. But when viability is reached, she said, the woman can still achieve a goal of not being pregnant while allowing the fetus to survive.

Abortion opponents argue that the viability framework is inappropriate. In an amicus brief, the Family Research Council contends that it “arbitrarily discounts states’ substantial interest in pre-viability fetal life,” adding there’s a “scholarly consensus” that the line is arbitrary. Scott Stewart, Mississippi’s solicitor general, argued on Wednesday that the viability line “is not tethered to anything in the Constitution, in history, or tradition. It’s a quintessentially legislative line.” He added that some state legislatures may think it’s a reasonable place to draw the line, while others may want to pick another time frame.

Did the court give any indication of how it might rule in the case?

Conservative justices appear inclined to uphold the Mississippi law after hearing nearly two hours of oral arguments that included clashes over the framework of medical viability. Justice Samuel A. Alito Jr. summed up the argument for dismantling the viability framework, saying the fetus “has an interest in having a life” and asking “that doesn’t change, does it, from the point before viability to the point after viability?”

But the other side argued that viability provides a cutoff to the contentious issue of when to allow abortions — and one that has been legal precedent for nearly five decades.

“I don’t think there’s any line that could be more principled than viability,” U.S. Solicitor General Elizabeth B. Prelogar said in response to a question about an alternative marker from Justice Neil M. Gorsuch. “|I think the factors the court would have to think about are what is most consistent with precedent; what would be clear and workable; and what would preserve the essential components of liberty interest. Viability checks all of those boxes, and has the advantage as well [of] being a rule of law for 50 years.”