Florida bail hearings in capital and life cases are called "Arthur hearings," after the case State v. Arthur, 390 So. 2d 717(1980.)

In Florida, to establish that "proof of guilt is evident" and the "presumption is great," the state's burden is aptly described in the 2011 ruling in State v. Wyche:

It "is actually a greater degree of proof than that which is required to establish guilt merely to the exclusion of a reasonable doubt." ... Even when the prosecution's evidence is sufficient to convict on a capital or life offense, but there is some doubt arising from other evidence, contradictions, or discrepancies, this exacting standard is not met and the accused is entitled to reasonable bail.

Thus a Florida defendant charged with a crime punishable by death or life imprisonment has a substantive constitutional entitlement to bail unless the prosecution can show that proof of his guilt is evident or presumption of his guilt great, i.e., unless the prosecution can, at a pretrial hearing, establish the defendant's culpability to a standard higher even than that required for a sustainable conviction at trial. (my emphasis.)

This is because Article I, section 14, of the Florida Constitution provides:

Unless charged with a capital offense or an offense punishable by life imprisonment and the proof of guilt is evident or the presumption great, every person charged with a crime or violation of municipal or county ordinance shall be entitled to pretrial release on reasonable conditions. If no conditions of release can reasonably protect the community from risk of physical harm to persons, assure the presence of the accused at trial, or assure the integrity of the judicial process, the accused may be detained.

As a Florida appeals court ruled in Elderbroom v. Knowles, 621 So. 2d 518, 520 (Fla. Dist. Ct. App. 4th Dist. 1993):

Indeed, the state is held to a degree of proof greater than that required to establish guilt beyond a reasonable doubt.

Another Florida appeals courts ruling the same way: Stallings v. Ryan, 979 So. 2d 1167 (Fla. Dist. Ct. App. 3d Dist. 2008.)

In State v. Perry, 605 So. 2d 94, 97 (Fla. 3d DCA 1992), the court explained that even if the state's evidence is enough to convict at a jury trial, it may not meet the test for denial of bail.

Further, where the State's evidence is sufficient to convict for a capital or life offense but is arguably impeached in substantial respects by other evidence or is replete with substantial contradictions and discrepancies, the proof does not meet the standard. Accordingly, the accused in such a case would be entitled to pretrial bail as a matter of right for such offense.

The Perry Court, and later decisions, have referred to some of the language in Arthur as merely dicta and not overruling Florida's long and consistent precedent on the topic:

We do not view [the Arthur dicta] as overruling a long line of Florida Supreme Court decisions, not discussed or even involved in Arthur, which have consistently held that (1) "the degree of proof sufficient to deny an accused the right to bail in a capital [or life offense] case under our Constitution, to wit, proof that guilt is evident or the presumption of guilt is great is actually a greater degree of proof than that which is required to establish guilt merely to the exclusion of a reasonable doubt,"... and (2) where the state's evidence, although not insufficient to convict for a capital or life offense, is arguably impeached in substantial respects by other evidence or is rendered doubtful by substantial contradictions and discrepancies in the state's case, the proof is not stronger than beyond a reasonable doubt and, accordingly, the accused is entitled to pretrial bail as a matter of right for such offense....

There's also Kirkland v. Fortune, 661 So. 2d 395, 397 (Fla. Dist. Ct. App. 1st Dist. 1995), which cites a 1916 case holding:

The question is not whether the evidence adduced on an application for bail is sufficient to establish guilt beyond a reasonable doubt, but whether the evidence is sufficient to establish that degree of proof where the judge to whom the application is made may say that guilt is evident or the presumption is great, which is a greater degree of proof than that establishing guilt merely to the exclusion of a reasonable doubt.

The word "evident" is defined by Webster as "clear to the understanding and satisfactory to the judgment." Synonyms: "Manifest, plain, clear, obvious, conclusive." The word "manifest" is defined as follows: "To put beyond question of doubt."

In a trial this degree of proof is not required, for it not infrequently happens that upon a conviction the court will refuse to grant a new trial because there is evidence to support the verdict, although to his mind guilt may not have been established to the point of being manifest, obvious, beyond a question of doubt, yet it is to the court to whom application for bail is made, and his judgment is invoked as to the degree of proof established by the evidence, and not what a petit jury not yet impaneled may possibly decide as to the probative force of the evidence.

There are two stages to "Arthur hearings." In the first stage, the Court decides if the proof is evident and presumption great. Even if the judge finds the proof is evident or the presumption great that the accused committed a capital or life imprisonment offense, it only means that bail is not mandated. There may still be a second phase of the Arthur hearing, where the defendant can come forward with a showing as to why the court should exercise its discretion and grant bail.

It is the second phase of the Arthur hearing at which the court considers things like the defendant's ties to the community, resources, and danger that he might flee. If the judge decides bail is appropriate, he cannot set it in an amount that is beyond the defendant's resources to meet. Otherwise, the setting of bail would be no different than the denial of bail.

The purposes of bail are to ensure the appearance of the defendant at subsequent proceedings and protect the community against unreasonable danger from the defendant. According to Florida law, Fla. Stat. § 903.046,the judge considers:

(a) The nature and circumstances of the offense charged.

(b) The weight of the evidence against the defendant.

© The defendant's family ties, length of residence in the community, employment history, financial resources, and mental condition.

(d) The defendant's past and present conduct, including any record of convictions, previous flight to avoid prosecution, or failure to appear at court proceedings.

(e) The nature and probability of danger which the defendant's release poses to the community.

... (i) The nature and probability of intimidation and danger to victims.

....(k) Any other facts that the court considers relevant.

George Zimmerman has no prior convictions. He has substantial ties to the community, lives and works in the community, is married, and had been employed and a student up to the time of arrest. He turned himself in upon learning of the charges.

I've said a few times I won't be surprised if the state agrees to bail to avoid having to show its evidence before the Stand Your Ground hearing. If it does not agree to bail, I think the judge will grant it. If he doesn't, Zimmerman can file a habeas corpus petition to challenge the denial.