The Florida Supreme Court overturned decades of legal precedent on Monday in ruling that the State Constitution’s privacy protections do not extend to abortion, effectively allowing Florida to ban the procedure after six weeks of pregnancy.

But in a separate decision released at the same time, the justices allowed Florida voters to decide this fall whether to expand abortion access. The court ruled 4 to 3 that a proposed constitutional amendment that would guarantee the right to abortion “before viability,” usually around 24 weeks, could go on the November ballot.

The rulings encapsulated, in a single state on a single day, how the country has grappled with the abortion issue since the U.S. Supreme Court overturned the Roe v. Wade decision that recognized federal abortion rights in 1973.

The conservative-leaning court found 6-1 that a 15-week abortion ban enacted in 2022 was constitutional. That ruling — in response to a lawsuit brought by Planned Parenthood, the American Civil Liberties Union and several abortion providers — will allow a six-week ban enacted last year to take effect by May 1.

“Based on our analysis finding no clear right to abortion embodied within the Privacy Clause, Planned Parenthood cannot overcome the presumption of constitutionality and is unable to demonstrate beyond a reasonable doubt that the 15-week ban is unconstitutional,” Justice Jamie R. Grosshans wrote in the majority opinion.

In paving the way for the six-week ban, the court cemented the rapid transformation of Florida, once a destination for women seeking abortions in the American South, into a place with restrictive policies akin to those in surrounding states.

But allowing the ballot measure gave supporters of abortion rights a chance to continue their national campaign to preserve access to the procedure by giving voters the opportunity to directly weigh in on the issue. Ballot measures in favor of abortion rights have already succeeded in several states, including Ohio and Michigan.

“This is a historic day in the fight for abortion access in Florida,” said Lauren Brenzel, director for the Yes on 4 campaign that put forth the ballot measure. “No longer will decisions about abortion be left between politicians disconnected from the realities of everyday Floridians’ lives.”

Abortion rights groups in about 10 states are trying to put measures on the ballot to secure access; Florida is the largest of those states.

Historically, many women from Southern states with tighter restrictions on abortion have traveled to Florida for the procedure. They will now have to seek abortions much further away, perhaps in Virginia or Washington, D.C. Few women realize that they are pregnant at six weeks, and backers of abortion rights say the stricter ban, once effective, will amount to a near-total prohibition.

In its ruling allowing the six-week ban to take effect, a majority of the justices argued that past abortion cases had been wrongly decided based on an overly broad interpretation of the State Constitution’s privacy clause — an argument similar to the one the U.S. Supreme Court made in overturning Roe.

The privacy clause in the Florida Constitution states: “Every natural person has the right to be let alone and free from governmental intrusion into the person’s private life.” The Florida Supreme Court first ruled that it applied to abortion in 1989; in 2012, voters rejected an amendment that would have exempted abortion from constitutional privacy protections.

But on Monday, a majority of the justices said that voters did not understand the privacy clause to extend to abortion when they added it to the State Constitution in 1980, citing among other things the public and legislative debate at the time.

Justice Jorge Labarga, the lone dissenter, noted that the ruling would have far-reaching consequences.

“The impact of today’s decision extends far beyond the 15-week ban at issue in this case,” he wrote. “By operation of state statute, the majority’s decision will result in even more stringent abortion restrictions in this state.”

The justices narrowly approved the ballot measure, saying it complies with Florida requirements that it be clear and limited to a single subject. Those who dissented argued in part that the language in the ballot question is too vague and could lead to years of further litigation.

Neither of Monday’s rulings was a surprise: The seven-member court has moved to the right politically, with Gov. Ron DeSantis, a Republican, appointing four of the justices. But while the court had a Monday deadline to rule on the abortion measure, it faced no similar timeline to rule on the abortion ban.

By issuing both rulings on the same day, the court gave abortion opponents a sought-after decision narrowing privacy protections. But by also allowing a ballot measure to expand abortion access, it gave those groups little time to celebrate.

Immediately after the court ruled, opponents and proponents of the ballot measure accused the other side of being extreme, previewing their likely campaign messages.

Republican lawmakers who supported the 15-week and six-week abortion bans argued that the ballot measure would allow abortions late in pregnancy. Abortions after 21 weeks are extremely rare and usually follow severe medical diagnoses.

“This is not about government’s interference with abortion but about allowing abortion until the moment of birth,” said State Senator Erin Grall of Vero Beach, who sponsored the six-week ban.

Ms. Brenzel countered that it was the lawmakers who were out of step with a majority of Floridians. Public opinion polls have suggested that most Floridians believe abortions should be legal in most cases.

And Danielle Tallafuss, a Central Florida resident who had an abortion at 22 weeks after learning that her fetus had a life-limiting heart condition before the state restricted the procedure, said women should be able to make the decision to terminate a pregnancy with their doctors.

“My heart has been in turmoil since the Supreme Court overturned Roe v. Wade and Florida’s passage of a 15-week abortion ban,” she said. “Today I am filled with hope that residents will be able to vote in November to give abortion access back to the women of this state.”