Demonstrators hold signs in support of Trayvon Martin in Union Square Wednesday, March 21, 2012 in New York. Ten years ago when Trayvon Martin was fatally shot, Florida was one of the few states with “stand your ground” laws that eased use of deadly force in the face of danger. Now, upwards of 30 states have some form of the law and recent research indicates they're associated with more deaths _ as many as 700 additional gun killings each year, according to a study published this week in the Journal of the American Medical Association. (AP Photo/Mary Altaffer, File)
