Editor's Note: (This story was originally published in December 2021. It has been updated on May 4, 2022, following the leak of a draft opinion by Justice Samuel Alito.)
(CNN) A stunning leaked draft Supreme Court opinion that would overturn the landmark Roe v. Wade ruling and wipe out nationwide abortion protections that have lasted for half a century is sparking a sharp debate over the role of precedent in the American judiciary.
Supporters of upholding Roe point to the legal principle of stare decisis, which gives compelling weight to past decisions to bind or influence current cases. Advocates who want to overrule Roe say that it was wrongly decided at the time, and it belongs with other overruled decisions like Plessy v. Ferguson, which at the time upheld segregation in schools.
A CNN analysis of congressional data shows overruling the landmark abortion rights case would be unusual, but far from unprecedented: The Supreme Court has overruled more than 250 of its own cases throughout American history, including 45 that lasted longer than the nearly 50 years that Roe v. Wade has been in effect.
Half of the cases that have been overturned by the high court were overruled within two decades of the initial decisions, according to the analysis. The average case that was overruled by the Supreme Court stood for less than 30 years before being overruled.
Five out of every six cases overruled by the Supreme Court were overturned before reaching the 49-year mark of Roe v. Wade. Just 16% of overruled cases lasted as long as Roe.
The Supreme Court has not released a final ruling in Dobbs v. Jackson, but it is expected to do so by the end of June. No ruling is official until then, and the leaked copy published by Politico is labeled as a "first draft."
In it, Justice Samuel Alito writes that the court must be willing to reconsider and, if necessary, overrule its own decisions both in Roe and the 1992 Casey v. Planned Parenthood ruling.
"Stare decisis, the doctrine on which Casey's controlling opinion was based, does not compel unending adherence to Roe's abuse of judicial authority," Alito writes in the draft opinion. "Roe was egregiously wrong from the start. Its reasoning was exceptionally weak, and the decision has had damaging consequences. And far from bringing about a national settlement of the abortion issue, Roe and Casey have enflamed debate and deepened division."
"The Court has no authority to decree that an erroneous precedent is permanently exempt from evaluation under traditional stare decisis principles," Alito continues. "A precedent of this Court is subject to the usual principles of stare decisis under which adherence to precedent is the norm but not an inexorable command."
Former President Donald Trump nominated three conservative justices to the Supreme Court -- Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett -- all of whom acknowledged Roe v. Wade as precedent, but did not say whether they would uphold it or overturn it. During the 2016 presidential campaign, Trump promised that his nominees to the Supreme Court would overrule Roe v. Wade.
Acknowledging precedent is not the same thing as vowing to uphold that decision, even if only a few dozen cases have ever been overruled after standing for as long as Roe v. Wade.
The state of Mississippi is asking the 6-3 conservative court to overrule the landmark abortion rights case. The Mississippi law bans abortions after 15 weeks of pregnancy with no exception for rape or incest. The current standard, set by Roe v. Wade, is generally considered to be from 22 to 24 weeks.
A new ABC News/Washington Post survey released this week but conducted before the Alito draft was leaked found that Americans believe the landmark abortion rights case should be upheld by a two-to-one margin.
This story has been updated with additional information.