I thought Slaw readers might be interested in the actual text of the Florida legislation that, in theory at least, governs the Trayvon Martin case. Title XLVI, Chapter 776.012 governs "Use of force in defense of person":
A person is justified in using force, except deadly force, against another when and to the extent that the person reasonably believes that such conduct is necessary to defend himself or herself or another against the other’s imminent use of unlawful force. However, a person is justified in the use of deadly force and does not have a duty to retreat if:
(1) He or she reasonably believes that such force is necessary to prevent imminent death or great bodily harm to himself or herself or another or to prevent the imminent commission of a forcible felony; or
(2) Under those circumstances permitted pursuant to s. 776.013. . . .
776.013 (3) A person who is not engaged in an unlawful activity and who is attacked in any other place where he or she has a right to be has no duty to retreat and has the right to stand his or her ground and meet force with force, including deadly force if he or she reasonably believes it is necessary to do so to prevent death or great bodily harm to himself or herself or another or to prevent the commission of a forcible felony.
A further section, which I've not seen reported in the press, may go some way to explaining the fact that George Zimmerman was not arrested or charged after the shooting in that it would seem to place a heavier burden than normal on the prosecution contemplating the laying of charges:
776.032 (1) A person who uses force as permitted in . . . s. 776.013 . . . is justified in using such force and is immune from criminal prosecution and civil action for the use of such force, unless the person against whom force was used is a law enforcement officer, as defined in s. 943.10(14), who was acting in the performance of his or her official duties and the officer identified himself or herself in accordance with any applicable law or the person using force knew or reasonably should have known that the person was a law enforcement officer. As used in this subsection, the term “criminal prosecution” includes arresting, detaining in custody, and charging or prosecuting the defendant.
(2) A law enforcement agency may use standard procedures for investigating the use of force as described in subsection (1), but 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.
(3) The court shall award reasonable attorney’s fees, court costs, compensation for loss of income, and all expenses incurred by the defendant in defense of any civil action brought by a plaintiff if the court finds that the defendant is immune from prosecution as provided in subsection (1).
Canada's Criminal Code provisions on self-defence are found in sections 34 and 35, if you'd care to do a comparison.