Originally Published: 01 DEC 21 18:07 ET

By Ryan Struyk and Priya Krishnakumar, CNN

For nearly half a century, Roe v. Wade has stood as the law of the land.

Next year, all of that could change.

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 almost four dozen that lasted longer than the 48 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.

To be sure, the vast majority of cases decided by the Supreme Court are never overruled. But it's not uncommon — 45 cases have been overturned after serving as established precedent for at least 48 years. Roe, which was decided in January 1973, will reach its 49th anniversary in January 2022.

The state of Mississippi is now asking the 6-3 conservative court to overrule the landmark abortion rights case Roe v. Wade. A decision on the Mississippi law is expected by summer 2022.

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 separate law in Texas bans abortions after just six weeks.

A recent ABC News/Washington Post survey found that 60% of Americans believe the landmark abortion rights case should be upheld. Only 27% say it should be overturned.

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.

But 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.

Kavanaugh seemed to downplay the importance of precedent in oral arguments on Wednesday. "If you think about some of the most important cases, the most consequential cases in this Court's history, there's a string of them where the cases overruled precedent," he said, pointing to cases that overruled segregation and bans on same-sex intimacy. "The country would be a much different place" if the court had followed precedent, Kavanaugh said.

Justice Sonia Sotomayor shot back later: "Of all of the decisions that Justice Kavanaugh listed, all of them, virtually, except for maybe one, involved us recognizing and overturning state control over issues that we said belong to individuals." She also asked aloud about the political implications of overturning Roe: "Will this institution survive the stench that this creates in the public perception that the Constitution and its reading are just political acts?"

Five out of every six cases overruled by the Supreme Court were overturned before reaching that 48-year mark. But Roe v. Wade might soon join the short list of overruled cases that lasted nearly half a century before their reversals.