TALLAHASSEE — Florida's new death penalty law went on trial Thursday in the Supreme Court as a death row inmate asked for a life sentence, the state called for his execution, and a justice who's often part of a five-member court majority questioned the law's constitutionality.Hanging in the balance are the lives of all 390 death row inmates — and demands for justice by victims' families — as the court decides whether a decision by the U.S. Supreme Court must be applied retroactively, which would commute death sentences to life.The nation's highest court ruled Jan. 12 in the case of inmate Timothy Lee Hurst that Florida's death sentencing system was unconstitutional because it gave too little power to juries in capital cases. In that decision, the U.S. Supreme Court also told the state's highest court it must review the sentence of Hurst, 37, sentenced to die for the 1998 murder of Cynthia Harrison, the manager of a Popeye's fast-food restaurant in Pensacola where they both worked. Testimony showed that Hurst emptied the store safe and used the money to buy shoes and rings.The U.S. Supreme Court did not invalidate the death penalty itself, but Hurst's attorney, David Davis, argued that because Hurst was sentenced under a defective law, he should now be sentenced to life."You can't separate the punishment from the procedure," Davis said. "You can't have one without the other."In response to the Hurst decision, Gov. Rick Scott signed a legislative overhaul of the death penalty sentencing law (HB 7101) in March.Assistant Attorney General Carine Mitz countered that Hurst should still be executed because the Legislature addressed the defects in the old law."If the (Hurst) case were to be remanded (back to a trial court), it would have to be under the new statute," Mitz said. "I still don't think we have a problem."But Justice Barbara Pariente, who frequently is part of a five-member majority on the court, said she sees a big problem.Pariente expressed concern that the new law could violate the Eighth Amendment prohibition against cruel and unusual punishment because it requires the existence of only one of 16 aggravating factors under Florida law that make a defendant eligible for a death sentence.Florida's old law was a legal balancing act in which "sufficient aggravating factors," such as the severity of the crime or whether another crime was also being committed, are weighed against mitigating factors, such as the defendant's background or level of intelligence."If only one aggravator is needed in this state to put someone to death, we have a serious Eighth Amendment problem," Pariente said. "If we want a death penalty in Florida, we need it to be constitutional."The state disagreed."I don't think that the new statute is as detrimental as some might present," Mitz said. "I probably should have said it's actually better."Justice Charles Canady, a death penalty supporter who is frequently opposite Pariente and in the minority, noted that jurors in Hurst's case found two aggravating factors in recommending his execution by a 7-5 vote."We know the death sentence was based on two aggravators," Canady said.Long before the U.S. Supreme Court intervened, Pariente had questions about Hurst's case. The court upheld his death sentence in 2014 in a 4-3 decision in which Pariente' partial dissent was joined by justices Jorge Labarga, now the chief justice, and James Perry."I dissent from the majority's affirmance of Hurst's death sentence because there is no unanimous finding by the jury that any of the applicable aggravators apply," Pariente wrote in 2014. "The absence of juror unanimity in the fact-finding necessary to impose the death penalty remains, in my view, an independent violation of Florida's constitutional right to trial by jury."Because of the Hurst case, capital punishment in Florida is facing its greatest uncertainty since it was reinstituted in the 1970s.The last inmate executed was Oscar Ray Bolin, who was put to death Jan. 7, five days before the Hurst decision.Since then, the Florida Supreme Court has indefinitely delayed the executions of Michael Lambrix and Mark Asay, whose attorneys have also argued that their sentences should be reduced to life without parole.Attorney General Pam Bondi has identified 43 death sentences that are eligible to be reduced to life. Those 43 so-called "pipeline" cases involve inmates whose initial limited appeals, known as direct appeals, have not yet been heard by the Florida Supreme Court.Contact Steve Bousquet at [email protected] Follow @stevebousquet.