In her news conference announcing that George Zimmerman was being charged with second degree murder in the death of Trayvon Martin, Florida Special Prosecutor Angela Corey mentioned several times that self-defense is an "affirmative defense" under Florida law. She also said that "Stand Your Ground" is "a tough affirmative defense to overcome." See M. Alex Johnson, MSNBC, Zimmerman to plead not guilty to second degree murder (April 11, 2012). It will be "tough" for the prosecution because although Zimmerman has to introduce some evidence that he acted in self-defense, that doesn't mean that he has to convince the jury that he acted in self-defense. All he has to do is to create a "reasonable doubt" as to whether he acted in self-defense. A proposed amendment to the Florida Jury Instructions makes that perfectly clear.