Executions in Florida and the fate of prisoners on death row will remain on hold after a resounding ruling on Friday from the state’s highest court that the death penalty there is unconstitutional.

Capital punishment has been in limbo in the state since a US supreme court decision in January 2016 that Florida’s system was unconstitutional because judges had the final say on the death sentence, whereas that power should be held by juries.

Now Florida’s supreme court has ruled that a fix that lawmakers attempted in the spring is also unconstitutional.

The Florida justices ruled that death sentences cannot be handed down by a jury deciding in the majority, which was the essence of state lawmakers’ spring fix – the jury must agree unanimously.

The legislature’s rewriting of the law in May to allow juries to award the death penalty on the basis of a 10-to-2 decision was ruled unconstitutional by the state’s court.

Experts declared the decision a major blow to Florida’s death penalty and a further weakening of America’s fraying ties to the principle of capital punishment.

“I’m happy. This is an important ruling. My first reaction is relief that it’s going to require a unanimous decision from a jury to make the ultimate determination of whether or not someone should die,” said Rob Smith, director of the Fair Punishment Project at Harvard law school.

The legislature will now be forced back to the drawing board if it wants to rewrite the law again and keep the death penalty going in Florida.

It is believed lawmakers will not go into a session where this can happen until next spring, meaning that death sentences, and probably also executions, will continue to be on hold, Smith said.

“This decision confirms everything that we have known for years about the broken death penalty system in Florida,” said Smith. “What hits hard is realizing how many millions of dollars have been wasted across Florida for years and how much suffering has been caused to the families of victims who have to come to court over and over again because of overzealous prosecutors who knew that the statute was probably unconstitutional.”

The Florida supreme court issued two rulings at the same time on Friday. One held that the rewriting of the statute to allow a majority jury ruling on death was unconstitutional and the second ordered a new sentencing hearing for Timothy Hurst, the condemned murderer at the center of the legal row.

Hurst, who has been on Florida’s death row since 2000, could have his sentence commuted to life in prison. The state supreme court has not yet explained whether its ruling will apply to the almost 400 inmates already on Florida’s death row, or only to future cases.

Florida’s governor, Rick Scott, declined to comment while he digested the ruling, a statement from his office said.

“All current death sentences in Florida should be commuted to life in prison and this should have been done immediately after the US Supreme Court ruled that Florida’s death penalty statute was unconstitutional in January, 2016,” Mary Anne Franks, professor of law at the University of Miami school of law, wrote to the Guardian in an email.

The ruling will be a blow to the already-embattled Florida attorney general, Pam Bondi – who is caught up in a scandal over whether her decision not to investigate the now-defunct Trump University was in any way connected to presidential candidate Donald Trump’s donation to her re-election campaign.

Rob Smith said he believed many given the death sentence in Florida were among “the most impaired, most broken and most vulnerable” members of society.

“And yet Florida declares that the death penalty is supposed to be reserved for the worst of the worst,” he said.

Florida had been unusual in its system of allowing a judge to decide the death sentence. The jury could make a recommendation but the judge had the final say. The rewriting of the statute in May to change the decision to one made by a jury – but allowing a majority decision – also kept Florida among a small minority of states. Most that still have the death penalty require a unanimous jury decision on death.

Alabama has the majority jury system but recently declared that it is constitutional. Delaware recently decided that its majority jury system was unlawful and needs to be changed.

“It’s a slow process, but the death penalty is gradually dying itself across this country,” Jeff Kirchmeier, professor of law at City University of New York school of law, said.

“Florida has had the death penalty for decades and they are still having problems getting it right. I would like states like these to realize that there are other punishments that are just as effective as the death penalty,” he added.