When does self-defense cross the legal line?
It's a question that is being asked all over America in the wake of last month's shooting death of Florida teenager Trayvon Martin.
Martin, 17, was shot and killed on February 26 by George Zimmerman, 28, a self-appointed neighborhood watch captain in the Orlando suburb of Sanford.
Zimmerman says he started trailing Martin as the boy walked home from a convenience store because Martin, who is African-American, looked suspicious. Zimmerman says he stopped following Martin and was returning to his car when the boy attacked him. Zimmerman claims he shot Martin in self-defense.
Zimmerman has not yet been arrested or charged with a crime, and that has sparked public outrage across the country.
Most states have laws that protect a person who uses reasonable force to defend themselves. Florida has what is known as a "stand your ground" law that allows a person to shoot someone they believe is threatening them. However, most of these laws are subject to quite a bit of interpretation.
"There can be plenty of gray area in these cases," says attorney Martin Sweet of legal information website THELAW.TV . "For example, you might use force because you believe the person you're attacking has a gun. But what if it turns out he doesn't have a gun?"
In the Trayvon Martin case, Martin did not have a weapon, which has fueled public outrage even further.
Self-defense cases can also become complicated when the court has to decide whether the force a threatened person used was truly reasonable.
"If somebody punches you in a bar, then in many states you would legally be able to defend yourself by throwing a punch of your own," explains Sweet . "However, retaliating by hitting that person on the head with a beer bottle could be seen as unreasonable force."
Some states also have laws that include a "duty to retreat." This means that deadly force is only acceptable in situations where a person is unable to safely retreat from the scene. In most cases, a "castle exception" holds that a person is not obligated to retreat if he is threatened in his home.
In Florida, there is no duty to retreat even when a person is threatened outside his home.
While this seems to help Zimmerman's case, it remains to be seen whether he will be charged in Martin's death. A Florida grand jury will investigate the case in April.