Even under the old retreat duty, prosecutors needed to show your route of escape was truly safe; the rule did not require you to turn your back on someone who might well catch up and do you harm. By many accounts, Trayvon had the upper hand in the scuffle between the two before the gunshot (according to his attorney, Zimmerman had a broken nose).
If Zimmerman claimed he had no safe way to disengage from the beating, prosecutors might have had trouble establishing the "safe line of retreat" required under the old law.
There's a pattern here. If Sanford police lacked probable cause to charge Zimmerman under the post-'05 law, they most likely also lacked probable cause under the older law. (Whether they should have worked harder to develop evidence of probable cause is a separate question.)
Even if Zimmerman started the fight (by pushing Martin, say), Florida law still allows him to argue that the response from Martin was such that he feared for his life and that he had no realistic opportunity to escape. Sean Bugg sums up that possibility this way: "Did you start a fight and get your ass kicked? Bang bang bang! Problem solved." Not quite, because you have to reasonably fear "death or great bodily harm," and you have to exhaust "every reasonable means of escape" (or, alternatively, you can disengage from your opponent and make it clear you no longer want to fight, only to be attacked again). That is the old "duty to retreat" standard, and "stand your ground" does not enter into it.
Bugg assumes Zimmerman started the fight, arguing that "you don't have the right—or, at least shouldn't have the right—to chase down a person on a dark street, start a confrontation, get your ass kicked and then shoot that person dead." As I noted last week, the authors of Florida's "stand your ground" law seem to agree that Zimmerman made himself the aggressor by following Martin for no good reason. Northern Kentucky University law professor Michael J.Z. Mannheimer is not so sure, noting that even someone who sets the stage for a violent confrontation by breaking the law will not necessarily be deemed the "initial aggressor." Mannheimer illustrates that point with U.S. v. Peterson, a 1973 decision by the U.S. Court of Appeals for the D.C. Circuit:
The victim trespassed on the defendant's land and stole the windshield wipers from the defendant's vehicle, a misdemeanor. The defendant went into his house, retrieved a gun, returned, and told the victim not to move. The victim approached the defendant menacingly with a wrench and the defendant shot and killed him. The court held that the question of who was the initial aggressor was a question for the jury, rejecting the defendant's argument that the victim's trespass and misdemeanor theft made him the aggressor as a matter of law.
By contrast, it is not clear that Zimmerman broke the law in any way prior to the fight. "Does following someone, even with the intent only to ask questions, render Zimmerman the 'initial aggressor?'" Mannheimer asks. "I would think not." In any case, given Zimmerman's description of the fight—that Martin punched him in the face hard enough to knock him down, repeatedly slammed his head against the pavement, and tried to grab his gun—a jury might conclude the shooting was justified, based on the "duty to retreat" standard that applies to someone who "initially provokes the use of force against himself," even if it believed Zimmerman started the fight. Mannheimer adds that "it might be the case that Martin himself was justified in using physical force because he reasonably believed that Zimmerman was about to do him harm," in which case "both may have had a valid self-defense claim."
Only one of them is alive to make it, of course, which means we will never hear Trayvon Martin's version of events. That is both an advantage for Zimmerman, who cannot be contradicted by the teenager he killed, and a disadvantage, since the tragic outcome predisposes people to think Zimmerman overreacted. That may indeed be what happened, but if so his actions are hardly tantamount to deliberately running a man over with a pickup truck just for kicks.