WASHINGTON — The Supreme Court struck down a restrictive Louisiana abortion law Monday, a dramatic victory for abortion rights activists and a bitter disappointment to conservatives in the first showdown on the controversial issue since President Trump’s remake of the court.

As with other recent liberal victories at the court, Chief Justice John Roberts Jr. was key in the 5-4 decision. He joined the court’s liberals rather than his conservative colleagues, including Trump’s appointees, Justices Neil Gorsuch and Brett Kavanaugh.

Roberts said the Louisiana law could not stand given the court’s 2016 decision to overturn a similar Texas law, which required doctors who perform abortions to have admitting privileges at nearby hospitals.

“The legal doctrine of stare decisis requires us, absent special circumstances, to treat like cases alike,” Roberts wrote in concurring with the decision.

“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.”

Roberts’s vote was all the more striking because he dissented in the Texas case.

He said he continues to “believe that the (Texas) case was wrongly decided.” But he said the question was whether to “adhere to it in the present case.”

It was perhaps the most dramatic example of Roberts’s new role as the pivotal member of the court. It indicated that while he supports restrictions on abortion – his solo opinion in fact tightened a concession won in the Texas case – he is unready at this point to overhaul the court’s jurisprudence supporting the right of a woman to choose the procedure.

The White House issued a statement criticizing what it called an “unfortunate ruling.”

“The Supreme Court devalued both the health of mothers and the lives of unborn children by gutting Louisiana’s policy that required all abortion procedures be performed by individuals with admitting privileges at a nearby hospital,” the statement from press secretary Kayleigh McEnany said.

She added: “Unelected justices have intruded on the sovereign prerogatives of state governments by imposing their own policy preference in favor of abortion to override legitimate abortion safety regulations.”

Justice Stephen Breyer wrote the main decision in the case, just as he had in the Texas decision four years ago. Justices Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan joined him, which resulted in this: No women wrote about the case, but all six male justices did.

The question was whether Louisiana’s 2014 law requiring doctors at abortion clinics to have admitting privileges at nearby hospitals unduly burdens women’s access to abortion. Practitioners have said it has proved impossible for most of the doctors to acquire the privileges, leaving only one eligible to perform the procedure.

Breyer said the law is “almost word-for-word identical” to the Texas law. In that case, now-retired justice Anthony Kennedy joined the court’s four liberals to form a majority in what was its most important endorsement of abortion rights in 25 years.

The court’s 2016 decision in Whole Woman’s Health v.

Hellerstedt said the admitting-privileges requirement “provides few, if any, health benefits for women, poses a substantial obstacle to women seeking abortions, and constitutes an ‘undue burden’ on their constitutional right to do so.”

Hospitalization after an abortion is rare, all sides agree, and the lack of admitting privileges by the doctor who performed the procedure is not a bar to the woman getting needed medical care.

Breyer’s decision Monday read like a replay of the 2016 decision. The admitting privileges requirement provided no benefit to protect women and was likely to mean two of Louisiana’s three clinics would have to close, imposing onerous problems for thousands of women across the state, Breyer wrote.

“The requirement places a substantial obstacle in the path of a large fraction of those women seeking an abortion for whom it is a relevant restriction,” he wrote.

Roberts disagreed with Breyer’s reasoning. But he nonetheless concluded: “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. For that reason, I concur in the judgment of the Court that the Louisiana law is unconstitutional.”

Each of the court’s four most consistent conservatives wrote separately to describe their disagreement.

“Today a majority of the court perpetuates its ill-founded abortion jurisprudence by enjoining a perfectly legitimate state law and doing so without jurisdiction,” wrote Justice Clarence Thomas. “As is often the case with legal challenges to abortion regulations, this suit was brought by abortionists and abortion clinics. Their sole claim before this court is that Louisiana’s law violates the purported substantive due process right of a woman to abort her unborn child.”

As he has in the past, Thomas said the court’s landmark ruling in Roe v. Wade was “made out of whole cloth, without a shred of support from the Constitution’s text.

Our abortion precedents are grievously wrong and should be overruled.”

Justice Samuel Alito Jr. denied that Louisiana had not shown there were benefits to having doctors acquire admitting privileges.

And he embraced an argument raised late in the litigation by Louisiana: that abortion clinics should not have standing to protest the regulations.

“The idea that a regulated party can invoke the right of a third party for the purpose of attacking legislation enacted to protect the third party is stunning,” Alito wrote. “Given the apparent conflict of interest, that concept would be rejected out of hand in a case not involving abortion.”

But Roberts joined Breyer and the others in saying the court had allowed such standing for years, and Louisiana had waived the argument early in the litigation.

Gorsuch criticized the court’s decision-making, and said that its usual rules go by the wayside when “a case touching on abortion enters the courtroom.” Kavanaugh said he would have sent the case back to the lower court for additional fact-finding on the doctors’ attempts to acquire admitting privileges and whether any of the three abortion clinics would close.

Louisiana has adopted more abortion restrictions than any other state, and Gov. John Bel Edwards, a Democrat, said he was disappointed with the outcome.

“Throughout my career and life as a pro-life Catholic, I have advocated for the protection, dignity and sanctity of life and will continue to do so,” Edwards said in a statement. “While I voted for the law in question and am disappointed, I respect the U.S. Supreme Court’s decision and trust that Louisiana and our nation will continue to move forward.”

Abortion rights activists were happy, but wary of what comes next.

“This is a big win that vindicates what we’ve said all along, which is that the Louisiana admitting privileges law is unconstitutional,” said Nancy Northup, president of the Center for Reproductive Rights, which led the fight against the law. “This is a victory for the people of Louisiana and the rule of law, but this case never should have gotten this far.”

The Supreme Court will soon be called upon to take up other abortion restrictions passed in the states, including nearly complete bans on the procedure.

“The court’s ruling today will not stop those hellbent on banning abortion,” Northup said. “We will be back in court tomorrow and will continue to fight state by state, law by law to protect our constitutional right to abortion. But we shouldn’t have to keep playing whacka-mole.”