http://www.alternet.org/civil-liberties/10-ways-system-rigged-protect-cops-who-kill
"The answer is both simple and complex. On the simple side, the system is substantially rigged in favor of letting officers off the hook for using excessive force in the line of duty—especially if they say they needed to protect themselves. On the complex side are how the various stages of the process tilt toward covering up what abusive police have done, as well as biases built into the legal system that shield police from prosecution."
