As for innocent people being imprisoned or put on death row in the US, let me say that there has never been a case where DNA or other evidence has proved that anyone was wrongly put to death. Some have won new trials and been freed, but that doesn't mean they were innocent. More likely it means evidence has been lost, witnesses died or disappeared and the prosecution now lacks the means to prove its case beyond reasonable doubt. I hear a lot of stories about criminal trials from my daughter and her boyfriend, both of whom are prosecutors. People on trial for serious crimes are usually dirtbags of the first order, but juries never hear about prior arrests or convictions, threats against witnesses or police or other bad behaviors unless it has a direct bearing on the specific charge in question. In deciding what to allow during trial, judges deliberately err on the side of the defendant in order to minimize the likelihood of a conviction being overturned. Juries are instructed that the state must prove its case beyond a reasonable doubt in order for a guilty verdict to be returned. A single stubborn, irrational juror can cause a hung jury. Delays usually work in favor of the defendant since evidence and witnesses' memories or availability seldom improves with age. It's my impression that on the average, criminals receive only a portion of the punishment they deserve, and few if any get more than they deserve. If that weren't the case, prisons would be much nicer places than they are.