(Karen Bleier/AFP/Getty Images)

The Supreme Court on Friday decided to hear its most consequential abortion case in nearly a quarter of a century, agreeing to determine how far states may go in regulating the procedure without violating a woman’s constitutional rights.

It could be one of the court’s most far-reaching rulings on the morally and politically divisive subject, and it will land just months before Americans choose a new president. The divide over protecting the unborn and safeguarding the right of a woman to choose is among the starkest differences between the Republican and Democratic candidates.

The case from Texas, which is likely to be heard by the court in early March, will affect women across the nation. Numerous states have enacted restrictions that lawmakers say protect a woman’s health but that abortion providers contend are merely a pretext for making it more difficult to obtain an abortion or even making the procedure unavailable within a state’s borders.

Abortion providers say full implementation of the Texas law passed in 2013 would reduce from 42 to 10 the number of clinics in the nation’s second-largest state. The court took no action on a case from Mississippi, where a similar law would close the state’s only clinic if it were allowed to proceed. That law was stopped in a lower court.

The outcome of the Texas case will turn on an interpretation of the court’s ruling nearly 25 years ago in Planned Parenthood v. Casey . It said states had a legitimate interest in regulating abortion procedures but could not impose an “undue burden” on a woman’s right to terminate a pregnancy before fetal viability.

Included in the description of such a burden was “unnecessary health regulations that have the purpose or effect of presenting a substantial obstacle to a woman seeking an abortion.”

Justice Anthony M. Kennedy is the only justice remaining of the three who wrote the Casey standard in 1992 and will again be the pivotal justice in deciding whether the state restrictions violate it.

The Texas law, one of the most comprehensive in the nation, requires among other things that abortion facilities meet the standards required of surgical centers. It also says that doctors who perform abortions at clinics have admitting privileges at a nearby hospital.

“The common-sense measures Texas has put in place elevate the standard of care and protect the health of Texas women,” state Attorney General Ken Paxton (R) said in a statement after the Supreme Court accepted the case.

“The state has wide discretion to pass laws ensuring Texas women are not subject to substandard conditions at abortion facilities,” he said. “The advancement of the abortion industry’s bottom line shouldn’t take precedence over women’s health, and we look forward to demonstrating the validity of these important health and safety requirements in Court.”

But abortion providers say the regulations are nothing more than a ruse by antiabortion legislators and governors.

“Today the Supreme Court took an important step toward restoring the constitutional rights of millions of women, which Texas politicians have spent years dismantling through deceptive laws and regulatory red tape,” said Nancy Northup, president of the Center for Reproductive Rights (CRR), which is representing the clinics.

“For more than four decades, the Supreme Court has agreed that the U.S. Constitution protects every woman’s right to make her own decisions about her health and family,” she said. “Now the court must reject the schemes of politicians who believe the Constitution and the court’s precedents do not apply to them.”

Abortion rights activists have been reluctant to force the Supreme Court to make a decision on state restrictions on abortion, fearing that the conservative court would not give an answer they would like.

But Northup said the Texas restrictions are so tough that there was no choice. A woman in El Paso would have to travel 500 miles for an abortion at the nearest clinic, she said. She added that the court has never ruled on a restriction so far-reaching.

The abortion providers enlisted the support of organizations such as the American Medical Association and the American College of Obstetricians and Gynecologists.

Those groups, along with other medical associations, also asked the court to strike down the law, saying the costly surgical-center requirements and admitting-privileges requirements “do nothing to protect the health and safety of women and are incongruous with modern medical practice.”

“Women’s access to high-quality, evidence-based abortion care should not be limited by laws enacted under the guise of patient safety but that, in fact, harm women’s health,” the brief states.

It says that abortion is one of the safest medical procedures and that the vast majority are conducted in a doctors’ offices. It also says having admitting privileges at a local hospital for a doctor who performs abortions is unnecessary in the rare instances where a woman would require hospital treatment.

As a practical matter, religiously affiliated hospitals or those simply wanting to avoid controversy do not extend such privileges.

But lawmakers have pointed to medical officials who favor both the surgical-center and admitting-privileges requirements, and courts have split on whether it is up to the judiciary to second-guess the decisions of the state that extra protection for women is needed.

According to the CRR, 10 states have enacted laws requiring admitting privileges, six of which have been blocked by the courts.

Six states have enacted surgical-center requirements on clinics providing first-trimester abortions, four of which are in effect.

Virginia is one of the four, with rules implemented when the commonwealth had a Republican governor and attorney general. But at Democratic Gov. Terry McAuliffe’s urging, the state Board of Health in September relaxed the requirements for existing clinics. New clinics will need to meet some of the new construction standards.

The new laws are part of a swell of new restrictions on abortion passed in recent years. The CRR says 38 states have enacted at least one new law restricting abortion access since 2011.

Different three-judge panels of the U.S. Court of Appeals for the 5th Circuit, which covers Texas, Louisiana and Mississippi, arrived at conflicting views of the state laws in question.

One panel let Texas’s law largely take effect. But the other blocked Mississippi’s admitting privileges law because it would have meant the state’s only abortion clinic, in Jackson, would be forced to close. The panel said it was not enough that women seeking abortions could go to a neighboring state for the procedure.

The issue before the court will produce an outpouring of conflicting studies and amicus briefs, but it seems likely that they will be directed toward an audience of one: Kennedy.

He, along with two now-retired justices, Sandra Day O’Connor and David H. Souter, wrote the opinion in Casey. At the time, the compromise was seen as a great victory for abortion rights advocates because it rejected a bid by conservatives to overturn 1973’s Roe v. Wade, which recognized a woman’s right to abortion.

But Casey also acknowledged a state’s interest in protecting unborn life and regulating abortion.

Kennedy has said he is personally opposed to abortion, and in 2007 he sided with conservative justices to uphold the federal Partial-Birth Abortion Ban Act. He wrote the opinion in that case, Gonzales v. Carhart, and it is the language in that decision that has given rise to some of the new state restrictions.

The Supreme Court already has shown its divisions in earlier litigation about the Texas law. In 2014, the court refused to step in after a preliminary decision allowed the law to go into effect. The liberal justices — Ruth Bader Ginsburg, Stephen G. Breyer, Sonia Sotomayor and Elena Kagan — objected.

But in June, the court did issue a stay of a final decision by the 5th Circuit, which would have meant that the 19 clinics still operating in Texas would have been reduced to 10. This time it was the court’s consistent conservatives — Chief Justice John G. Roberts Jr. and Justices Antonin Scalia, Clarence Thomas and Samuel A. Alito — who were outvoted.

In both decisions, Kennedy’s was the prevailing vote.

The Texas case is Whole Woman’s Health v. Cole.