How quickly should courts change the law? Florida tests the limit.

When the Florida Supreme Court ruled late last month that a unanimous jury is not required for the state to hand down a death sentence, the decision reverberated in the state prisons that house hundreds of felons already sentenced to death.

The legal wrangling over their fate overnight became “chaos,” says Marty McClain, a death-penalty lawyer.

After all, only four years earlier, Florida had struck down the power of judges, not juries, to decide whether or not to execute convicted felons. That ruling followed a landmark U.S. Supreme Court finding that Florida’s system for capital sentencing was unconstitutional and led nearly 100 inmates on death row there to challenge their sentences.

But a new conservative majority on Florida’s highest court has begun taking a shredder to this and other seemingly settled rulings, part of a national rollback of what conservatives see as an era of liberal judicial activism. That ideological rollback is embodied in President Donald Trump’s appointment of 187 U.S. judges, including two to the Supreme Court, since 2017. Under his watch, three U.S. appeals courts have flipped from liberal to more conservative majorities.

In its Jan. 23 verdict, the Florida Supreme Court said it had “got it wrong” in 2016 when it curbed the power of judges to effectively overrule split juries on capital cases. That case, Hurst v. State, was supposed to have a “limited practical effect on the administration of the death penalty,” Chief Justice Charles Canady wrote. But he said it had led to legal maneuvering that was undermining “decades of settled Supreme Court and Florida precedent.”

Critics say the court’s abrupt reversal – the 2016 ruling was more than a decade in the making – has caused chaos for inmates on death row and attorneys like Mr. McClain. Some argue it violates the legal concept of stare decisis, which holds that rulings that overturn established law should be “well thought-out and pretty rare,” says Kenneth Williams, a professor at the South Texas College of Law Houston.

Life and death

In states that practice capital punishment, juries who find a suspect guilty are required to weigh the “aggravating sentences” and decide whether they justify execution or not. Florida’s twist on this safeguard is that judges aren’t bound by a jury’s advisory finding and can hold a separate hearing and decide that the death penalty is justified.

This power was struck down, however, in 2016 by the U.S. Supreme Court, which said in its decision that the Sixth Amendment “requires a jury, not a judge, to find each fact necessary to impose a sentence of death. A jury’s mere recommendation is not enough.”

This then led to Hurst v. State, in which the Florida Supreme Court set a new precedent for the state’s death-penalty system.

The new interpretation by Florida’s highest court serves to “remove your friends and neighbors from the awesome power of the state to kill one of your neighbors,” says Eric Freedman, a Hofstra University law professor.

The reason for the about-turn is the court’s makeup: Republican governors have replaced four of the justices who ruled on the 2016 case under Florida’s mandatory retirement law, tilting it to conservatives.

Whether justified or not, the impulse in Florida to rewrite law as soon as a new court is seated shows how judges taking cues from national political tides – and the U.S. Supreme Court itself ­– can affect lives in profound ways.

These are judges “who have a very narrow interpretation of the Constitution and they will come out with really narrow decisions,” says law professor Stephen Harper, director of the Death Penalty Clinic at Florida International University in Miami. “That means the country is reverting to a much more conservative outlook and jurisprudence – more conservative than I think the public wants, or is.”

History’s scrapyard

To be sure, the U.S. legal landscape is littered with scrapped ideas. Rulings like Plessy v. Ferguson (1896) that enshrined “separate but equal” racial segregation and Bowers v. Hardwick (1986) that upheld a state law against homosexual acts have long been overturned. Such reexaminations of settled law require careful reading of the Constitution but also the ability for appeals courts to absorb evolving societal norms into the law.

By contrast, Florida’s reconstituted court took only a year or so to reverse the 2016 verdict and failed to show “powerful reasons” to do so, says Professor Harper, a former public defender in Miami-Dade County. The issues at hand were “way too close.”

Mr. Freedman agrees. “There is nothing wrong with the concept that you want to reexamine old precedents to see if they make sense,” he says. “But does it make institutional, practical sense, both in terms of where we are now and where we are likely to be?”

To many conservative thinkers, the answer is yes. The Senate Republicans Communications Center tweeted “Merry Christmas!” in applauding the latest wave of White House appointments to the federal bench in December.

These judges’ extended terms mean the effects of their rulings could be felt for decades to come. But the impacts may not be as revolutionary as progressives fear, because conservative jurists don’t make up a monolith and, moreover, will be leery of upending established case law, say analysts.

Take the Supreme Court: The four liberal justices tend to rule more as a pack than the other five. That suggests an awareness, says Mr. Freedman, that the power of the court comes in large part from its ability to project stability.

Moreover, “there is a split of thinking on [the power of precedent] in conservative circles,” writes Brian Fitzpatrick, who studies judicial selection at Vanderbilt Law School in Nashville, in an email.

This divide is seen in the reasoning of late Justice Antonin Scalia, who “thought that every day could not be a new day in the law,” putting a strong emphasis on stare decisis, Mr. Fitzpatrick points out. Whereas “people like Justice [Clarence] Thomas think it is wrong to prolong mistaken decisions – that his oath is to the Constitution, not to what his colleagues said about the Constitution.”

Challenging judicial consensus

This readiness to challenge precedent was seen last year when the U.S. Supreme Court overturned 40 years of labor law by making it illegal to force non-union workers to pay union fees. Meanwhile, states like Alabama and Georgia have passed laws intended to set up a challenge to the seminal Roe v. Wade decision that legalized abortion. Given that one Texas state judge has already ruled “Obamacare” unconstitutional, some progressives fear that conservatives hope to stack the courts in order to have the health care law overturned at the federal level.

“How can we order our lives if the law is constantly changing” in a cavalier manner, asks Mr. Williams, the Houston law professor. “If it becomes completely unpredictable, it becomes almost anarchy.”

Floridians, for one, are feeling the effects of a whipsaw state Supreme Court, says Daniel Goldberg, legal director at the Alliance for Justice, a progressive judicial advocacy group in Washington, D.C. Last year it blocked Miami Beach’s minimum wage ordinance on the grounds that it preempted state and federal authority to set a minimum wage.

“That means that 24,000 Miami workers are losing a total of $117 million annually. Talk about real-world impacts,” says Mr. Goldberg, referring to estimates of how much the ordinance would have raised earnings.

Florida has 384 inmates on death row, one of the highest of all states. Last month’s ruling has scrambled the work of capital defense attorneys, who were challenging the soundness of sentences based on a judge’s discretion to overrule a jury.

“A death sentence can’t be arbitrary, can’t be struck by lightning,” says Mr. McClain. “This is about the importance of finality.”