Q. When can I use my handgun to protect myself?
A. Florida law justifies use of deadly force when you are:
Trying to protect yourself or another person from death or serious bodily harm;
Trying to prevent a forcible felony, such as rape, robbery, burglary or kidnapping.
Using or displaying a handgun in any other circumstances could result in your conviction for crimes such as improper exhibition of a firearm,
manslaughter, or worse.
Example of the kind of attack that will
not justify defending yourself with deadly force: Two neighbors got into a fight, and one of them tried to hit the other by swinging a garden hose. The neighbor who was being attacked with the hose shot the other in the chest. The court upheld his conviction for aggravated battery with a firearm, because an attack with a garden hose is not the kind of violent assault that justifies responding with deadly force.
Q. What if I see a crime being committed?
A. A license to carry a concealed weapon does
not make you a free-lance policeman. But, as stated earlier, deadly force is justified if you are trying to prevent the imminent commission of a forcible felony.
The use of deadly force must be absolutely necessary to prevent the crime.
Also, if the criminal runs away, you cannot use deadly force to stop him, because you would no longer be "preventing" a crime. If use of deadly force is not necessary, or you use deadly force after the crime has stopped, you could be convicted of manslaughter.
http://licgweb.doacs.state.fl.us/weapons/self_defense.html
Florida law also provides that the use of deadly force is
not justified if the defendant is charged with an independent forcible felony, and the defendant was attempting to commit a felony
or the defendant initially provoked the use of force against himself.
http://www.criminaldefenseattorneytampa.com/FloridaDefenses/DeadlyForceSelfDefense.aspx