If you’ve been trying to make sense out of the blizzard of information about the Florida shooting death of 17-year old Trayvon Martin, here’s a very good explainer at Mother Jones: The Trayvon Martin Killing, Explained.

The more we learn about this case, the more it looks like a serious miscarriage of justice. Trayvon Martin was gunned down by a vigilante who ignored 911 instructions not to follow the young man, while he was simply walking home from the store.

How is it possible that the alleged shooter, George Zimmerman, was not even detained for killing Martin? Because Florida conservatives and the NRA pushed through broad “stand your ground” laws, which make it incredibly easy to claim self-defense in cases like this; all the shooter has to say is that he felt threatened — whether there was really a threat or not. And 17 other states have now followed suit.

Under then-Gov. Jeb Bush, the state in 2005 passed a broad “stand your ground” law, which allows Florida residents to use deadly force against a threat without attempting to back down from the situation. (More stringent self-defense laws state that gun owners have “a duty to retreat” before resorting to killing.) In championing the law, former NRA president and longtime Florida gun lobbyist Marion Hammer said: “Through time, in this country, what I like to call bleeding heart criminal coddlers want you to give a criminal an even break, so that when you’re attacked, you’re supposed to turn around and run, rather than standing your ground and protecting yourself and your family and your property.”

Again, the Sunshine State was the trendsetter: 17 states have since passed “stand your ground” laws, which critics call a “license to kill” or a “shoot first” law. The law has been unpopular with law enforcement officers in Florida, since it makes it much more difficult to charge shooters with a crime and has regularly confounded juries in murder cases; many Orlando-area cops reportedly have given up investigating “self-defense” cases as a result, referring them to the overloaded state attorney’s office for action. A 2010 study by the Tampa Bay Times found that “justifiable homicides” had tripled in the state since the law went into effect.