The law required abortion providers to obtain hospital admitting privileges, but critics, including national abortion rights groups, say it was created to shut down clinics.
Roberts had dissented in Whole Women's Health, which he noted in his concurrence. "But, nonetheless, [he] ruled against the law yesterday and as Justice Thomas pointed out this case shouldn't even be in court".
Carrie Severino, president of the Judicial Crisis Network, reacts to the court's "frustrating decision" on Louisiana's abortion restrictions.
Kristen Waggoner, general counsel for Alliance Defending Freedom, said women who want abortions "have the same right to competent and quality care as patients involved in other surgical procedures".
However, there was plenty of evidence that getting admitting privileges can be hard.
Abortion rights supporters welcomed the ruling.
Ilyse Hogue, president of NARAL Pro-choice America, called the decision "a win for women in Louisiana who will continue to have access to the time-sensitive abortion care they need".
In a 5-4 ruling, the justices did the opposite.
Yet earlier this month the court expanded equal protection rights to gay and transgender people, and sustained protections for certain undocumented immigrants that President Trump had sought to end.
Instead, Mr Roberts said that he was not prepared to reverse the precedent set by the court's 2016 decision - made before Trump's justices arrived - rejecting an identical Texas law.
However, with Chief Justice Roberts siding with the liberal wing of the court today, it shows conservatives may be further away than they thought from any significant changes to Roe v Wade. Critics said this would have limited access to abortions and placed an undue burden on women.
In that 2016 case, Breyer wrote that the admitting-privilege 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".
Associate Justices Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan joined Breyer in the opinion. Each filed a dissenting opinion. He also said the court's previous abortion opinions on which the latest ruling was based "created the right to abortion out of whole cloth, without a shred of support from the Constitution's text. Our abortion precedents are grievously wrong and should be overruled". And he did recognize the burdens that women face in states with restrictive abortion laws.
Missouri has some of the strictest abortion laws in the country. The U.S. Senate confirmed Gorsuch in April 2017 and Kavanaugh in October 2018.
Sachs blocked the law a day after it was supposed to take effect.