At issue is whether to reverse the court's nearly half-century-old decision, Roe v. Wade, and subsequent decisions declaring that women have a constitutional right to terminate a pregnancy.

Transcript

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An epic argument at the U.S. Supreme Court today. At issue - whether to reverse the court's nearly half-century-old decision Roe v. Wade and subsequent decisions declaring that people have a constitutional right to terminate a pregnancy. NPR legal affairs correspondent Nina Totenberg reports.

NINA TOTENBERG, BYLINE: Mississippi's law banning abortions after 15 weeks is a direct challenge to Roe. Until now, all the court's abortion decisions have upheld Roe's central framework - that a woman has a constitutional right to abortion in the first two trimesters of her pregnancy when the fetus cannot survive outside the womb, usually between 22 and 24 weeks. Mississippi's law bans abortion after 15 weeks. A separate law would ban abortions after six weeks. And while the six-week ban is not at stake in this case, the state is now asking the Supreme Court to reverse all of its prior abortion decisions and to return the abortion question to the states.

It's not the first time the court has been asked to reverse Roe. The last major challenge was in 1992 in a case called Planned Parenthood vs. Casey. And as we look at the issues before the court today, it's worth listening to what three justices said back then in reaffirming what they called the central holding of Roe. First Justice Sandra Day O'Connor.

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SANDRA DAY O'CONNOR: Our obligation is to define the liberty of all, not to mandate our own moral code.

TOTENBERG: Then Justice Anthony Kennedy.

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ANTHONY KENNEDY: Our cases recognize the right of the individual, married or single, to be free from unwarranted governmental intrusion into matters so fundamentally affecting a person as the decision whether to bear or beget a child.

TOTENBERG: And lastly, Justice David Souter.

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DAVID SOUTER: The factual premises on which it rests are no different today from those on which the ruling rested initially. So to overrule in the absence of the most compelling reason would subvert the court's legitimacy beyond any serious question.

TOTENBERG: Those justices, all appointed by Republican presidents, were, however, all centrist conservatives. And today's Supreme Court supermajority of six justices, to a man and woman, are all dramatically more conservative and all with records opposing abortion rights. Mississippi contends that Roe and Casey were egregiously wrong and undemocratic rulings. Here's the state attorney general, Lynn Fitch, speaking to the "Explicitly Pro-Life" podcast.

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LYNN FITCH: This needs to be given back to the states. The unelected judiciary don't need to be making those decisions for us. We all elect our legislators and then, you know what? They're accountable.

TOTENBERG: But lawyer Julie Rikelman will tell the justices, that's wrong.

JULIE RIKELMAN: The very essence of a constitutional right is that it is not up to the legislatures. It's a right that we all have that legislatures cannot take away from us.

TOTENBERG: While she agrees the court did allow states to regulate abortion to further an interest in life, she adds that because abortion is a constitutional right, the one thing the state cannot do is ban a woman's abortion right prior to fetal viability. Mississippi says it put its 15-week ban into place in part because abortions are more dangerous later in pregnancy. But American Medical Association President Gerald Harmon notes that childbirth is far more dangerous than abortion.

GERALD HARMON: We know that there is a risk of death during or after childbirth that's substantially more than the risk of death from a medically sanctioned termination or abortion.

TOTENBERG: That said, for abortion opponents, there are moral issues at stake here. Lawyer Charles Cooper filed a brief siding with the state and points to what he calls new scientific facts.

CHARLES COOPER: Discoveries of when a fetus begins to form the physiology of a human with fingers and appendages and it can make sucking sounds all before viability, when a unborn child can begin to feel pain - these are all scientific realities that the people of the states are perfectly entitled to take into consideration.

TOTENBERG: But those are not scientific realities, according to briefs filed by just about every major medical association in the country. They dispute the notion of fetal pain pre-viability, noting that the neural connections in the brain that are required to feel pain have simply not developed before 24 weeks gestation. While some of today's argument may involve that question, the justices will largely focus on Roe and Casey, whether there's a constitutional right to abortion and whether, after nearly a half-century, the court should reverse itself. Charles Cooper.

COOPER: There's rarely been, in American jurisprudence, a decision that has been as widely criticized as wrong and even egregiously wrong as Roe vs. Wade.

TOTENBERG: Cooper says that Roe is as wrong as the court's decision in 1896 allowing segregation of the races - a decision that took more than a half-century to reverse.

COOPER: In my view, the justices of the court take an oath to protect and defend the Constitution, not their precedents.

TOTENBERG: And he says the text, history and tradition of the 14th Amendment does not support any right to abortion. How could it, he asks, when at the time the amendment was ratified in 1868, 30 out of 37 states banned abortion? Rikelman counters that the 14th Amendment is focused on life after birth, and others have noted it guarantees rights to those, quote, "born or naturalized" in the United States.

RIKELMAN: There is the explicit protection for liberty in Section 1 of the 14th Amendment. The Constitution also doesn't mention the words marriage or contraception or intimate relationships. And all of those have been protected by the court under the liberty clause, including the ability to make basic decisions about our bodies, for over 100 years.

TOTENBERG: What's critical to remember, Rikelman argues, is that the court has long said that a woman's liberty interests are unique when it comes to pregnancy. Her body and her health is deeply affected by pregnancy, as is the course of her life. As Cooper sees it, if the court overturns Roe even without explicitly saying so, the country will return to the natural order of things as the founders intended. Rikelman, however, says the result would be chaos, with about half the states poised to either ban abortion entirely or ban it at extremely early points in pregnancy. Nina Totenberg, NPR News, Washington.

(SOUNDBITE OF MAMMAL HANDS' "WRINGER") Transcript provided by NPR, Copyright NPR.