Both sides are telling the Supreme Court there's no middle ground in Wednesday's showdown over abortion. The justices can either reaffirm the constitutional right to an abortion or wipe it away altogether. 

Roe v. Wade, the controversial landmark 1973 ruling that declared a nationwide right to abortion, is facing its most serious challenge in 30 years in front of a court with a 6-3 conservative majority that has been remade by three appointees of President Donald Trump.

“There are no half measures here,” said Sherif Girgis, a Notre Dame law professor who once served as a law clerk for Justice Samuel Alito.

A ruling that overturned Roe and the 1992 case of Planned Parenthood v. Casey would lead to outright bans or heavy restrictions on abortion in 26 states, according to the Guttmacher Institute, a research organization that supports abortion rights.

The case being argued Wednesday comes from Mississippi, where a 2018 law would ban abortions after 15 weeks of pregnancy, well before what opponents say is considered 'viability.' The Supreme Court has never allowed states to ban abortion before the point at roughly 24 weeks when a fetus, unborn baby, can survive outside the womb.

The justices are separately weighing disputes over Texas' much earlier abortion ban, at roughly six weeks, though those cases turn on the unique structure of the law and how it can be challenged in court, not the abortion right. Still, abortion rights advocates were troubled by the court's 5-4 vote in September to allow the Texas law, which relies on citizen lawsuits to enforce it, to take effect in the first place.

The Supreme Court had never before even agreed to hear a case over a pre-viability abortion ban. But after Justice Ruth Bader Ginsburg's death last year and her replacement by Justice Amy Coney Barrett, the third of Trump's appointees, the court said it would take up the case.

Trump had pledged to appoint “pro-life justices” and predicted they would lead the way in overturning the abortion rulings. Only one justice, Clarence Thomas, has publicly called for Roe to be overruled.

The court could uphold the Mississippi law without explicitly overruling Roe and Casey, an outcome that would satisfy neither side.