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Mississippi’s attorney general told the Supreme Court on Thursday that Roe v. Wade was “egregiously wrong” and should be overturned as she urged the justices to allow a controversial law that bars most abortions after 15 weeks to go into effect.

“The conclusion that abortion is a constitutional right has no basis in text, structure, history, or tradition” state Attorney General Lynn Fitch told the justices in a new brief, launching the opening salvo in the most important abortion-related dispute the court has heard in decades.

Fitch said the case for overruling Roe is “overwhelming.”

Roe v. Wade is the 1973 landmark Supreme Court decision legalizing abortion nationwide prior to viability, which can occur at around 24 weeks of pregnancy.

RELATED: How Trump and McConnell set the final pieces for the Supreme Court to reconsider Roe v. Wade

The case reignites the debate surrounding abortion and comes as states across the country, emboldened by the conservative majority and the addition of Justice Amy Coney Barrett to the high court, are increasingly passing restrictive abortion-related regulations, hoping to curb the constitutional right first established in 1973 in Roe and reaffirmed in 1992 when the court handed down Planned Parenthood v. Casey.

The justices deliberated for months whether to take up the Mississippi dispute, finally announcing their decision last spring and sending shock waves through groups supporting abortion rights, who are fearful that the conservative majority – bolstered with three of President Donald Trump’s appointees – will upend long-established constitutional protections for access to abortion.

Oral arguments will likely be heard in the late fall or early winter, with a decision expected by next June, in advance of the midterm elections.

Now that Mississippi has taken the step of asking the justices to overturn precedent, all eyes will be on the conservatives to see how far they are willing to go. In June 2020, Chief Justice John Roberts sided with the liberals to block a controversial Louisiana law, but, critically, he left open the possibility that other states in different circumstances might be able to pursue similar restrictions.

On the other side of the conservative spectrum, Justice Clarence Thomas reiterated his belief, in dissent, that Roe is “grievously wrong for many reasons.”

As for the three liberals, led by Justice Stephen Breyer, who has so far turned away liberal demands to retire, they will attempt to limit the decision and preserve as much precedent as possible.

Blocked by lower courts and arguments over viability

Mississippi’s Gestational Age Act, passed in 2018 but blocked by two federal courts, allows abortion after 15 weeks “only in medical emergencies or for severe fetal abnormality” and has no exception for rape or incest. If doctors perform abortions outside the parameters of the law they will have their medical licenses suspended or revoked and may be subject to additional penalties and fines.

Fitch said the law “rationally furthers valid interests in protecting unborn life, women’s health, and the medical profession’s integrity,” adding, “It is therefore constitutional.”

A district court blocked the law in a decision affirmed by a federal appeals court.

“In an unbroken line dating to Roe v. Wade, the Supreme Court’s abortion cases have established (and affirmed and re-affirmed) a woman’s right to choose an abortion before viability,” a panel of judges on the 5th US Circuit Court of Appeals said in December 2019. “States may regulate abortion procedures prior to viability so long as they do not ban abortions,” the court held and concluded that “the law at issue is a ban.”

Mississippi Gov. Tate Reeves, a Republican, has said the law is a “vehicle” for the high court to revisit Roe v. Wade.

“The question is not are you going to overturn Roe v. Wade, the question is: The science has changed and therefore it makes sense for the court to review their decisions from the past and this is a vehicle in which for them to do it,” Reeves told CNN’s Jake Tapper on “State of the Union” last month.

Fitch suggested that the court no longer look to viability as a line dividing when a state can regulate the procedure. She argued Thursday that medical knowledge and “factual developments” have now “undercut that line.”

“Scientific advances show that an unborn child has taken on the human form and features months before viability,” she said in the court filing, and added that “states should be able to act on these developments.”

The Center for Reproductive Rights is representing Jackson Women’s Health Organization, the only licensed abortion facility in Mississippi, and the clinic’s medical director, Sacheen Carr-Ellis, who are challenging the law. Lawyers for the center will respond to Mississippi’s appeal later this year.

Last year the group had urged the justices to allow the lower court opinion to stand, arguing that Supreme Court precedent makes clear that before viability “it is up to the pregnant person, and not the State, to make the ultimate decision whether to continue a pregnancy.”

This story has been updated with additional details.