Florida has a statutory provision that grants "immunity" to people who are justified in the use of force. If that person is sued, civilly, the plaintiff has to pay the defendant's legals costs and all other costs and fees.
Usually, a criminal court judge finds immunity, but the same could happen in a civil court, even at the conclusion of the trial.
The burden of proof for finding immunity is "more likely than not" that defendant's story (in this case, Zimmerman) is correct. The opposition does not get to use conjecture, they must have positive evidence.
Thank you, very informative.