After the shooting of Trayvon Martin last spring, and its justification under Florida's "stand-your-ground" law, legislation that protects shooters acting in self-defense has come under increased scrutiny. Florida was the first state to adopt a "stand-your-ground" law or "Castle doctrine" (as in "your home is your...") in 2005, and Missouri followed two years after.
Before Castle doctrine laws went into effect, people who were being attacked or robbed were legally mandated to retreat, if possible. But the laws allow a property owner to use deadly force against an intruder or assailant if they believe their life is in danger, without fear that it may result in a civil or criminal suit. When someone is confronted with "unlawful force" (which is undefined in Missouri law), they may respond with "lethal force".
Earlier this year the Post-Dispatch reported seven fatal shootings in 2011 in St. Louis that were protected under Castle doctrine. It doesn't seem to matter that in several of the cases, no one's life was actually in danger.
Missouri's law also gives absolute immunity from civil suits to anyone using a firearm in real or perceived self-defense; it includes the award of attorney's fees, court costs, and all reasonable expenses incurred by a defendant in defense of any civil action brought by a plaintiff.
This isn't the wild, wild west but when you can pull a gun and shoot on someone who don't look right, it sure starts to feel like it is.