A divided U.S. Supreme Court on Monday ruled that Louisiana's abortion clinic restrictions, which threatened to leave only one abortion clinic operating in the state, unconstitutionally burden a woman's right to an abortion.

Justice Stephen Breyer led the 5-4 majority, joined by Justices Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan, Chief Justice John Roberts Jr. was the key vote; he concurred in the outcome, writing that the facts in the Louisiana case mirrored the facts in a Texas case that the justices found in 2016 also burdened a woman's right to abortion.

"The result in this case is controlled by our decision four years ago invalidating a nearly identical Texas law," wrote Roberts in his concurrence in the judgment. "The Louisiana law burdens women seeking previability abortions to the same extent as the Texas law, according to factual findings that are not clearly erroneous."

Roberts also stated: "The legal doctrine of stare decisis requires us, absent special circumstances, to treat like cases alike. The Louisiana law imposes a burden on access to abortion just as severe as that imposed by the Texas law, for the same reasons. Therefore Louisiana's law cannot stand under our precedents."

Separate dissenting opinions were filed by Justices Samuel Alito Jr., Clarence Thomas, Neil Gorsuch and Brett Kavanaugh. Thomas wrote: "Today a majority of the court perpetuates its ill-founded abortion jurisprudence by enjoining a perfectly legitimate state law and doing so without jurisdiction. "

The decision by the Supreme Court was a victory for abortion rights advocates who have vigorously opposed in other states the nearly identical requirement imposed by Louisiana: that all abortion physicians have hospital admitting privileges within 30 miles of the abortion facility.

" We're relieved that the Louisiana law has been blocked today but we're concerned about tomorrow. With this win, the clinics in Louisiana can stay open to serve the one million women of reproductive age in the state," Nancy Northup, president of the Center for Reproductive Rights, said in a statement. "But the court's decision could embolden states to pass even more restrictive laws when clarity is needed if abortion rights are to be protected."

If the Louisiana law were enforced, a federal district court found that only one physician at one of the state's three clinics would remain to provide services for an estimated 10,000 women seeking abortions each year.

The ruling is likely to energize anti-abortion groups to engage in another round of lobbying for the admitting privileges requirement in additional states.

The Louisiana case, June Medical Services v. Russo, was the first abortion-related case to come before the court's newest justices, Gorsuch and Kavanaugh. The case was closely watched for how the two justices would rule and what they might say. Equally important were the potential implications of the justices's treatment of their 2016 precedent in a nearly identical case—Whole Woman's Health v. Hellerstedt. In that case, Roberts voted in dissent.

In Whole Woman's Health, Justice Anthony Kennedy joined the court's four liberal justices in a decision by Justice Stephen Breyer striking down Texas's 30-mile hospital admitting privileges requirement because, they said, it served no medical benefit at all and burdened women's right to choose abortion.

Some of Louisiana's supporting amici had urged the justices to narrow or outright overrule the 2016 decision. And one of them—Americans United for Life—called on the court in its brief to re-examine the landmark abortion rights decisions Roe v. Wade and Planned Parenthood of S.E. Pennsylvania v. Casey.

In a cross-petition filed by Louisiana, the state challenged the high court's holdings for four decades that abortion providers have third-party standing to challenge abortion regulations on behalf of their patients.