Central to understanding the George Zimmerman case is the idea of self-defense, or Justification.. The entire "stand-your-ground law" issue is only a subpart of the discussion. It isn't a new defense; it merely alters the rules.
Traditionally, a defendant is allowed to use deadly force to repel deadly force. In most jurisdictions, the defendant is required to attempt to retreat before using deadly force unless he is in his home (the so-called Castle Doctrine, named for the adage that "a man's home is his castle"). This duty to retreat, or diffuse the situation, is removed in "stand-your-ground" jurisdictions.
Pennsylvania maintains the traditional approach to self-defense, referring to it as "Justification."
The Self-Defense / Justification Process in Court
First: the Defendant raises the defense that he was justified in using deadly force.
Second: the Commonwealth must show, beyond a reasonable doubt, that the defendant did not act in justifiable self-defense.
Third: the Jury must decide what kind of force was used by the defendant (deadly or non-deadly) Pennsylvania defines deadly force as "force that, under the circumstances in which it is used, is readily capable of causing death or serious bodily injury. "Serious bodily injury" is bodily injury that creates a substantial risk of death or that causes serious permanent disfigurement or protracted loss or impairment of the function of any bodily member or organ." (Pa. SSJI (Crim) 9.501)
This definition excludes force that is only deadly in an unexpected way. Shooting someone is deadly force. Slapping someone - unless the slapper is a World Champion Heavyweight Slapfighter - isn't deadly force, even it if leads to death.
Fourth: The Commonwealth must prove any of three propositions:
(i) that the defendant did not actually believe he was in danger of death or serious bodily injury such that he needed to use deadly force to defend himself at that moment; or, that while the defendant actually believed he needed to use such force, his belief was unreasonable in light of all the circumstances known to him. (Pa. SSJI (Crim) 9.501)
Jurors are typically further cautioned as follows:
"[A] person is justified in using deadly force against another not only when they are in actual danger of unlawful attack but also when they mistakenly, but reasonably, believe that they are. A person is entitled to estimate the necessity for the force he or she employs under the circumstances as he or she reasonably believes them to be at the time." (Pa. SSJI (Crim) 9.501)
(ii) that in the same encounter with the alleged victim, the defendant engaged in conduct that demonstrated his intent to cause death or serious bodily injury, and by that conduct, he provoked the use of force against him. (Pa. SSJI (Crim) 9.501)
or (iii) that the defendant knew that he could avoid the necessity of using deadly force with complete safety by retreating, but that he failed to do so.
As you can see, there are four (or five, depending on your interpretation) critical points at which the Commonwealth must prove something beyond a reasonable doubt. Failure to meet this burden at any of these critical points necessarily results in a Not Guilty verdict.
In a Pennsylvania trial for similar alleged offenses, the jury would be presumed to have concluded the prosecution failed at one of these critical points (once a burden has not been met in the process, deliberation is to cease and a Not Guilty verdict is to be rendered).
No Easy Answers in Self-Defense Cases
My sense over the weekend has been that the anger isn't about the Zimmerman case per se. That "local crime story in Florida" is a proxy. It is hopefully serving as a catalyst for a discussion about race and justice in America. Unfortunately, I suspect most Americans lack the vocabulary to discuss race, privilege, and justice. We are steeped in a self-referential mythology about melting pots and blind justice. These stories we tell ourselves serve a purpose when they bind together people of disparate backgrounds in a common community, but they also tend to prevent real reform.
I read somewhere, and have misplaced the citation (if you wrote it, tell me and I'll credit it to you) that "[t]his [the verdict] is basically saying that if you are racistly afraid of someone, you have no obligation to check your fear as irrational. And that your own racism is in fact considered reasonable enough to be considered a reason for self defense."
Assuming you accept this idea, which I'm not saying I do or do not, this puts it in the hands of the jury to use their common sense and life experience to determine if a defendant's belief the he is in imminent danger of death or serious injury is reasonable. If the jury really did conclude that George Zimmerman was motivated by racism and that this was a valid response, then reform is not going to happen in the realm of the system and must take place in the realm of culture.
I will just conclude by saying that I take comfort in the idea that our system of justice, while far from perfect, is designed to allow the occasional guilty man to walk free. This, to me, is far preferable to locking up the occasional innocent man. In that regard, the system works. That being said, as Melissa Harris Perry's father signed her birthday cards, "the struggle continues."