The Fox affiliate in Tampa reports that a man who claims to have witnessed part of the fight between Trayvon Martin and  George Zimmerman says he saw the 17-year-old student on top of the 28-year-old neighborhood watch volunteer, who was wearing a red sweater. "The guy on the bottom who had a red sweater on was yelling to me, 'Help, help," said the man, who asked to be identified only as John, "and I told him to stop and I was calling 911....When I got upstairs and looked down, the guy who was on top beating up the other guy was the one laying in the grass, and I believe he was dead at that point." This account, which John reportedly shared with police, is consistent with the grass stains on Zimmerman's shirt, his bloody nose, and the cut on the back of the head. It backs up Zimmerman's claim that the cries captured in the background of a 911 call came from him, not Martin. Citing those screams, a lawyer for Martin's family claimed Zimmerman had shot Martin "in cold blood" as the teenager begged for his life.

Even if John's account is accurate, it does not necessarily mean Zimmerman was justified in shooting Martin. But it suggests that the right to "stand your ground" protected by Florida's much-maligned self-defense law, which critics have blamed for the Sanford Police Department's decision not to arrest Zimmerman, may be irrelevant in this case. If Martin tackled Zimmerman, who as a result feared serious injury or death (perhaps because he believed Martin was about to grab his gun), the "duty to retreat" that was eliminated by Florida's law would not apply because Zimmerman would not have had an opportunity to escape. In fact, Zimmerman's lawyer says he does not plan to invoke the "stand your ground" principle.

Under Florida law, even if Zimmerman were deemed the aggressor (since he apparently provoked the fight by following Martin against the advice of a police dispatcher), he could still argue self-defense if he claimed the force used against him was so great that he reasonably believed that he was "in imminent danger of death or great bodily harm" and that he had "exhausted every reasonable means to escape such danger." He also might argue, although it does not seem to apply in this case, that he had withdrawn from physical contact with Martin and clearly indicated he did not wish to fight, after which Martin nevertheless continued or resumed the use of force. But neither argument hinges on the right to "stand your ground" when attacked in a public place.

Michael J.Z. Mannheimer, a law professor at Northern Kentucky University, argues that the Trayvon Martin case does highlight a problem with Florida's self-defense law, but it has nothing to do with the duty to retreat. Instead Mannheimer focuses on the section that says a person who legally uses force in self-defense "is immune from criminal prosecution," as opposed to letting him present that defense at trial. And while "a law enforcement agency may use standard procedures for investigating the use of force," the law says, "the agency may not arrest the person for using force unless it determines that there is probable cause that the force that was used was unlawful." That is the section the Sanford Police Department cited in explaining its decision not to arrest Zimmerman. These restrictions, Mannheimer argues, make it difficult to get at the truth in a case like this one:

This odd provision means that a person who uses deadly force in self-defense cannot be tried, even though the highly fact-intensive question of whether the person acted in self-defense is usually hashed out at trial. The law thus creates a paradox: the State must make a highly complex factual determination before being permitted to avail itself of the forum necessary to make such a determination.

Not only that, Section 776.032 provides immunity from arrest unless the police have "probable cause that the force that was used was unlawful." Again, the law creates a Catch-22: police cannot arrest the suspect unless they have probable cause, not just to believe there was a killing, but also that the killing was not in self-defense; and where, as is often the case, the defendant is the only living witness to the alleged crime, the police likely will not be able to form probable cause without interrogating the suspect.

While it's true that additional information may emerge after someone is charged and prosecuted, isn't that always the case? The problem is that arresting and prosecuting someone is in itself a kind of punishment and therefore to be avoided without some substantial reason to suspect he has committed a crime. The idea behind laws like this is that people who use force in self-defense should not have to worry about being prosecuted, even if they are ultimately acquitted. And if probable cause is the standard for all other arrests, why is that burden unreasonable in this case?

That is not to say Zimmerman should not be arrested. The Seminole County grand jury looking into the shooting may well conclude he should (which, of course, is not the same thing as determining that he is guilty). But if so, it's not clear the problem was an excessively restrictive law, as opposed to an insufficiently thorough police investigation or a questionable interpretation of the evidence.

Speaking of which, Morris Dees, founder of the Southern Poverty Law Center, recently likened Zimmerman's shooting of Martin to Deryl Dedmon's 2011 murder of James C. Anderson in Jackson, Mississippi. "You continue to see this around the country, the systematic targeting of black people," Dees told The New York Times. "That’s what happened here [in the Mississippi case], and that's what happened in Florida." Dedmon went out looking for black people to assault and deliberately ran over Anderson with a pickup truck. While Zimmerman's suspicion of Martin may have been influenced by the teenager's race, and his overzealousness created the circumstances that led to the teenager's death, there is no evidence that he "systematically target[ed]...black people." Martin may have died because of mutual misunderstandings, Zimmerman's unjustified panic, or Zimmerman's reasonable fear of death or serious injury (as Zimmerman claims). But Martin clearly did not die because of a premeditated racist rampage.