[jandrese]

Completely innocent people can still be convicted. Some even get put to death. One of the distressing things about the courts is that everybody can just "know" the guy is guilty, but in truth they know the evidence is crap. But luckily his defense is crap (good defense costs money) so they can get away with it. This happens time and time again and eventually the odds catch up to them and they've convicted a lot of innocent people.

Even worse is when the evidence is poor but they want to convict the guy anyway because he looks like a bad guy. "Even if he didn't do this, I know in my heart that he's guilty of other crimes."