Martin's shooting has unleashed a debate across America on the validity of these laws, which exist in some form in most states and which prosecutors and police have generally opposed as confusing, prone to abuse by criminals, and difficult to apply evenly. Others are concerned that the laws foster a vigilante, even trigger-happy mentality that might cause too many unnecessary deaths.
An Associated Press review of federal homicide data doesn't seem to bear that out. Nationwide, the total number of justified homicides by citizens rose from 176 in 2000 to 325 in 2010. Totals for all homicides also rose slightly over the same period, but when adjusted for population growth, the rates actually dipped.
At least two-dozen U.S. states since 2005 have adopted laws similar to Florida's, which broadly eliminated a person's duty to retreat under threat of death or serious injury, as long as the person isn't committing a crime and is in a place where he or she has a right to be. Other states have had similar statutes on the books for decades, and still others grant citizens equivalent protections through established court rulings.
While the states that have passed "stand your ground" laws continue to model them loosely after Florida's — Pennsylvania, Wisconsin and New Hampshire put expanded laws on the books last year — Florida is unique.
One area that sets Florida apart is the next step Zimmerman faces: With the police and prosecutor having weighed in, a judge will decide whether to dismiss the second-degree murder charge based on "stand your ground." If Zimmerman wins that stage, prosecutors can appeal.