Update: In March of 2017, Florida enacted a law prohibiting a death sentence unless the jury has unanimously recommended the death penalty.
In Hurst v. Florida, 577 U.S. ___ (2016), the U.S. Supreme Court found that Florida's capital punishment system violated the Sixth Amendment to the federal constitution.
Up until the decision, in a Florida death penalty case, the judge had the final say. After a conviction and a hearing, a jury would render an "advisory sentence." After that recommendation, the judge would independently make findings about aggravating and mitigating circumstances in order to determine whether to impose death.
The U.S. Supreme Court observed that any fact that exposes a defendant to a greater punishment than authorized by the jury's verdict must be determined by a jury. For a capital-punishment-eligible defendant, the maximum punishment authorized by a conviction—standing alone—was life imprisonment. So, the Court found Florida's system unconstitutional as requiring not the jury, but rather a judge, to "make the critical findings necessary to impose the death penalty."