David Kopel has this post at the Volokh Conspiracy making the same point I made yesterday.
Eventually, a grand jury will issue a report based on its investigation. In the meantime, there are two competing narratives. In one narrative, Zimmerman followed Martin, attacked him, and then murdered him. Let's call this the "M narrative." In Zimmerman's account, he followed Martin, caught up with him, and then left; while he was leaving, Martin attacked him, knocked him to the ground, and began slamming his head into the pavement. Let's call this the "Z narrative."
I am not making any judgment about which narrative is more plausible. The grand jury will do that. For now, it should be noted that neither the M narrative or the Z narrative has anything to do with a duty to retreat. The retreat issue would only be relevant if Martin were the aggressor, and Z had the opportunity to escape from Martin in complete safety. Then, and only then, would different state standards about retreat be relevant....
The core Florida law on deadly force in self-defense leads to clear results. If M is true, then Zimmerman's firing of the gun was a criminal homicide. If Z is true, the act was lawful self-defense. The results would be the same in every other state.
As far as I'm concerned, you have a duty to retreat if police officers tell you to do so, and this is precisely what they told Zimmerman to do. At least so we have been told by every media report I've read.
Decencyevolves: Zimmerman's story, as leaked by unknown individuals in local government, appears to be unravelling. A videotape of Zimmerman after the shooting does not contain evidence of blood or bruises and the police are blaming the state's attorney for the decision not to arrest him. Ugly stuff all around.