In Florida manslaughter is a lesser-included charge of second degree murder, so it was always inevitable that the jury would be read this instruction as well. Here, it is quite possible that the State may be able to prove the elements of the crime beyond a reasonable doubt–essentially that Zimmerman deliberately used force against Martin, and that Martin died as a result.
The challenge for the State, then, comes in the second half of the analysis in any self-defense case, and that is where the defendant claims that, yes, he did commit the acts with which he was charged but he was legally justified in doing so because he was acting in lawful self-defense. Self-defense is an absolute defense against conviction of any intentional crime, if accepted by the jury as true.
http://legalinsurrection.com/2013/07...-instructions/