The court, with a 4-2 ruling, "quashed" a ruling by a district appeals court on the state's Mandatory Delay Law that permitted the waiting period. In doing so it kept in place a temporary injunction that blocks enforcement of the law.
"Through the Mandatory Delay Law, the state impermissibly interferes with women's fundamental right of privacy," the majority said in the 59-page ruling.
The Florida office of the American Civil Liberties Union called the ruling a "win for Florida women."
"The burdens placed on a woman seeking an abortion by this mandatory delay law are medically unnecessary, potentially dangerous, and disproportionately burden poor and working women," said Nancy Abudu
, legal director for the ACLU of Florida. "This law had one purpose: to limit a woman's access to her constitutionally guaranteed medical care."
The court fight began after the law was enacted in June 2015. An abortion clinic in Gainesville, Bread and Roses Women's Health Center, brought the suit a day after the law was signed by Gov. Rick Scott, a Republican.
A lower court blocked the law, but an appeals court overruled the decision in February 2016. Two months later the state Supreme Court granted an injunction halting enforcement, and the lawyers argued the case before the justices in November.
In Thursday's ruling, Justice Barbara Pariente, writing for the majority, said the group that brought the suit had shown the law would require women to make second trips to medical facilities, which would increase the likelihood that their choices to get an abortion would not remain confidential.
Pariente also pointed out that no other procedure requires a mandated 24-hour waiting period. She added the state had not met its burden of proof.
"Because the right of privacy is a fundamental right within Florida's constitution, this court consistently has required that any law intruding on this right is presumptively unconstitutional and must be justified by a "compelling state interest," which the law serves or protects through the "least restrictive means," the justice wrote.
Dissent: No evidence the law is restrictive
Justice Charles Canady wrote the dissent, saying the appeals court decision should be affirmed on procedural grounds.
"This court has no evidence before it that a 24-hour hour waiting period is a significant restriction on the right to abortion," he wrote.
A recently appointed justice who did not hear arguments in the case did not vote.
John Stemberger, the president of the Florida Family Policy Council, told the Orlando Sentinel the high court's ruling was wrong.
"This is an irreversible, life-changing decision which has physical, emotional and psychological consequences and to have a 24-hour waiting period to make sure a woman knows what she's doing is not a substantial burden," Stemberger told the newspaper.
The high court said it was remanding the case to the appeals court for further discussion. It said the injunction would stay in place "pending a hearing on petitioners' request for a permanent injunction."
According to the Guttmacher Institute, a research and policy organization, 26 other states have laws requiring a waiting period
before an abortion.