in my experience, the jury part of the criminal justice system works pretty well. I live in a city with a small population and lots of crime, so I serve on juries for quite a few felony cases.

to some extent, my fellow jurors have been more or less what you might expect. most of them cared a lot more about going home than the outcome of the actual case and didn't appear to have highly developed critical reasoning skills. at the same time, they were a lot more skeptical than you give them credit for.

in most of the cases I've been a juror for, it looked like the accused probably did commit the crime. but prosecutors are pretty good at making it look that way. in the end, one or two jurors who actually cared found a couple holes in the prosecution's case and persuaded everyone to return not guilty and go home. I have yet to be part of a jury that returned a guilty verdict.

once the judge makes up their mind, that's it; that's your outcome. but it only takes one juror to throw a serious wrench in the gears, and this usually seems to favor the defense.