Abortion providers told the Supreme Court on Monday that approving a Mississippi law that bans most abortions after 15 weeks would “scuttle a half-­century of precedent and invite states to ban abortion entirely.”

They said in their brief that Mississippi’s request that the court overturn its 1973 decision in Roe v. Wade was based on the state’s hope that a “changed composition” of the court would reject years of legal precedent.

To do so, said lawyers for the state’s only abortion clinic and a doctor, would be to “abandon a rule of law that this Court has said uniquely implicates the country’s ‘confidence in the Judiciary.’ ” The quoted statement is from the court’s 1992 decision in Casey v. Planned Parenthood, in which the court upheld the essential holding of Roe and said states may not impose an undue burden on a woman’s right to the procedure.

The court’s review of the Mississippi law, which prohibits almost all abortions after 15 weeks of gestation, has taken on even more significance since the Supreme Court earlier this month let a more restrictive Texas law go into effect.

The court said it was not ruling on the constitutionality of that law, which authorizes private citizens to sue those who aid or abet an abortion after six weeks, only whether challengers had made a proper showing it should be stopped before taking effect.

Still, the 5-to-4 decision indicated the increasingly conservative court is more open to altering decades of Supreme Court precedents.

Since Justice Amy Coney Barrett replaced the court’s most outspoken advocate of abortion rights, the late Justice Ruth Bader Ginsburg, the court now has a 6-to-3 conservative majority. As a law professor, Barrett criticized Roe.

Mississippi argues that its law can be upheld without directly repudiating Roe and Casey. But after the change in the court’s makeup, the state last month boldly called for overruling both precedents.

Roe and Casey are unprincipled decisions that have damaged the democratic process, poisoned our national discourse, plagued the law — and, in doing so, harmed this Court,” Mississippi Attorney General Lynn Fitch (R) wrote in her brief.

Mississippi’s law has never gone into effect. Lower courts ruled the ban violates the court’s decision in Roe, which said states may regulate abortion but not ban the procedure before the fetus reaches viability, which is usually defined as 22 to 24 weeks of gestation.

The question the Supreme Court accepted is this: “Whether all pre-viability prohibitions on elective abortion are unconstitutional.”

The Center for Reproductive Rights, which is representing the Jackson Women’s Health Organization, said there would be massive repercussions if the court answered no.

“Accepting Mississippi’s request to abandon the viability line would turn back the clock for generations who have never known what it means to be without the fundamental right to make the decision whether to continue a pregnancy,” the center said in its brief.

“Any answer to the question presented other than a categorical ‘yes’ would shatter the understanding women have held close for decades about their bodies, their futures, and their equal right to liberty.”

Removing the pre-viability line, the clinics said, would open a “cascade” of state laws that set restrictions earlier and earlier, or even banned abortion.

“As abortion bans are enforced — or the threat of enforcement looms — large swaths of the South and Midwest would likely be without access to legal abortion,” the brief said. “Some people with the means to travel may be able to access legal abortion — but only after crossing multiple state lines.”

Others would resort to illegal abortions, the clinic said, or be forced to continue pregnancies they do not want or cannot afford.

In a statement Monday, Fitch said the clinic’s lawyers did not try to defend the original Roe decision.

“Nothing in constitutional text, structure, history, or tradition supports a constitutional right to abortion, nor is there a sound basis for the current viability guidepost that determines when states can enact limitations on abortion,” she said. “It is time to return policymaking to the people where they can address abortion policy in a way that empowers women and promotes life.”

The state’s brief said the court’s abortion jurisprudence puts it “at the center of a controversy that it can never resolve,” and that changes in society and science have undermined Roe.

“Today, adoption is accessible and on a wide scale women attain both professional success and a rich family life, contraceptives are more available and effective, and scientific advances show that an unborn child has taken on the human form and features months before viability,” the brief states.

It dismisses the argument that reproductive control is essential to what Ginsburg once called “a woman’s autonomy to determine her life’s course, and thus to enjoy equal citizenship stature.”

The clinic offers a rebuttal, saying no medical advance in the past 50 years has changed what scientists and doctors see as the point of viability, and saying that abortion is safer than childbirth.

“The comparative risk is even higher in Mississippi, where it is about 75 times more dangerous to carry a pregnancy to term than to have an abortion,” the brief states.

It noted two generations have never been without the right to terminate a pregnancy.

“The key insight of Casey and Roe is that the decision whether to end a pregnancy has deep constitutional roots in the fundamental rights to bodily integrity and personal autonomy in matters of family, medical care, and faith,” the clinic brief said.

“Resolving now to allow the government to control this intimate personal decision to the same extent as ordinary economic and social regulation would result in a radical displacement of personal liberty in favor of the power of the state.”

In a nod to modernity, the brief says in a footnote: “Although the term ‘women’ is used here and elsewhere, people of all gender identities may also become pregnant and seek abortion care.”

The overwhelming majority of abortions are performed in the first trimester, and the Jackson clinic provides abortions only up to 16 weeks. It says about 100 women annually have abortions in that week between what the law would prohibit and the clinic allows.

But it said that did not mean the change was insignificant, the brief argues. Mississippi’s current law allows abortions up to 20 weeks, but it has also passed a law that would ban the procedure after six weeks. If Roe is overturned, it has a law that would prohibit the procedure entirely.

Besides, the clinic argues, Casey and Roe protect any woman who wants an abortion. It argues constitutional rights, such as owning a gun or the speech rights of those who want to make campaign contributions, do not depend upon the number of individuals who want to exercise them.

The court has not yet scheduled arguments for Dobbs v. Jackson Women’s Health Organization. But it will not be before Nov. 29, as the court’s calendar before then already has been set.