When does acting in self-defence become murder?
It's the question dividing the United States after the killing of teenager Trayvon Martin by neighbourhood watchman George Zimmerman.
Tuesday's Dateline at 9.30pm on SBS ONE looks at Florida's controversial 'Stand Your Ground' gun law, which allows people to use lethal force if they feel threatened, not just in their own homes, but anywhere they have a legal right to be.
Since it was introduced in 2005 the rate of 'justifiable homicides' has almost tripled.
Reporter Amos Roberts looks at the effect that's had, both on those who've killed and the families of those who've died.
And he examines the controversy surrounding the law, with prosecutors saying justice should be served in court, not on the street.
See Amos's report on Tuesday at 9.30pm on SBS ONE, and read more now on the Dateline website.