Here's a long, detailed article on
the case of Cory Maye, a father who, upon having his apartment broken into without warning, fired three shots. One of them hit a police officer and he was placed on death row for awhile. Maye claims he had no idea they were police until after he fired the shots. Fortunately, he's been taken off death row and granted a new trial due to the incompetence of the defence and some shady tactics by the prosecution.
Ryan Frederick is another similar case; as with Maye, this resulted from a "confidential informant" who claimed Frederick had marijuana. In both cases, only enough for a misdemeanour charge was discovered, and in both cases a police officer (who, in this case, was dressed entirely in black) wound up dead because of the police's refusal to knock and announce themselves before conducting a raid. It's worth noting that these "confidential informants" are given substantial incentives to give people to hand over to the cops.
In another, possibly even more infuriating case,
a surveillance video of a police shooting is claimed to have suffered from a "technical problem" and has not been viewed or release. The 911 tapes have also mysteriously gone missing, and eyewitness accounts completely contradict the official police story.
Reading these cases has me livid with rage. The entire system is corrupt and needs to be completely overhauled.
Edit:
This map of botched drug raids from the Cato site is a sobering thing to look at.