The Supreme Court struck down a Louisiana law Monday that would have required abortion doctors to have admitting privileges at hospitals within 30 miles of their clinics.
Chief Justice John Roberts sided with the four liberal justices on the court in June Medical Services v. Russoto make it a 5-4 decision, granting abortion advocates a surprising victory.
The law, which was passed in 2014, has been barred from enforcement by a lengthy legal battle after Louisiana doctors and a medical clinic sued to get the law overturned. They argued that it placed an undue burden on a woman's right to an abortion by effectively eliminating nearly all of their options for legal abortion services, according to NBC News.
Advocates for the law, called the Unsafe Abortion Protection Act, argued that the law is intended to ensure the safety of patients seeking abortions.
A very similar case, Whole Woman's Health v. Hellerstedt, was argued before the Supreme Court in 2016 and a nearly identical Texas law struck down by then-Justice Anthony Kennedy's swing vote. Kennedy was later succeeded by conservative Trump appointee Justice Brett Kavanaugh, and conservatives hoped that this time around, the decision would swing in their favor.
Kavanaugh did side with the conservatives in Monday's dissenting opinion, but Roberts joined the majority.
Roberts claims precedent: The chief justice, who voted against striking down the Texas law in 2016, said that though he believed the court was wrong to do so then, he was bound by its precedent in this case. This legal principle is known as stare decisis.
"I joined the dissent in Whole Woman's Health and continue to believe that the case was wrongly decided," he wrote. "The question today however is not whether Whole Woman's Health was right or wrong, but whether to adhere to it in deciding the present case."
Thus he concluded: "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."
The decision is another disappointing one for conservatives who had hoped the nation's highest court would begin to rule in their favor with the addition of two new conservative justices during the Trump administration.
But in recent high-profile cases, including this one and two others regarding gay and transgender rights and the Deferred Action for Childhood Arrivals program, the chief justice has chosen to side with the liberals, appearing to embrace his new position as the court's swing vote.