The problem with "beyond the shadow of a doubt" as a legal standard is that it can never be applied in a real situation. In this country, possibly in yours too, judges instruct juries that it is not possible to determine facts to an absolute certainty. They can only be expected to apply the standard of beyond reasonable doubt. You cannot expect a judge or jury to determine whether a convicted killer is guilty beyond the shadow of a doubt, and therefore to be killed, when they have just finished convicting him. If there was any room for doubt in their minds they wouldn't, or shouldn't, have convicted him in the first place.

You're right, no society can afford a justice system that is paralyzed by the fear of getting it wrong, but I can tell you that there are people in jail who did not commit any crimes. Police are human. They usually do their best, but sometimes they make mistakes, and occasionally they do worse. Sometimes they lie, fabricate evidence, and hide evidence from the defence. Most prosecutors are honourable, but sometimes they aren't. Sometimes they develop tunnel vision and will go to any length to secure a conviction. Most juries are true to their oaths, but sometimes they aren't. You will never develop a system that guarantees there will be no wrongful convictions, but at least if the prisoner is alive you can say you are sorry.

On reflection, I owe Gnu an apology. I stand by everything I said, but I should have been less sharp in how I phrased it. My intention was to debate vigorously, but I can see how it came across as an attack.