True Defamation [pdf]

This depends on risk of course. You and society shouldn't be exposed to undue risk because of that assumption. But limitations on the offenders freedom to - for instance - perform certain jobs after their release should be decided by a court, not the general population.

Seems like the harm caused to a person through true defamation is outweighed by the benefit to society of holding people to account for bad behavior.

As you correctly say, 'there are no simple solutions to a problem this complex as human trust' but your last point is telling. Let's assume your villain provides proof well beyond reasonable doubt that he has actually changed for the better the fact remains that most people will always remember the fact—even many, many decades later. Moreover, I'd suggest that incident forever changes one's perception of the person even if it's almost imperceptibly small.

I claim no great expertise in human nature but from my observations of others and of myself I'd suggest that it is human nature to retain these negative images even if one has no logical reason whatsoever to do so.

It seems to me this is one of the basic underpinnings that drives defamation and why so many have such strong opinions about it.

For instance, to my knowledge I've never been defamed in public nor do I know of any reason why anyone would bother defaming me. I'm hardly controversial, and although I'm certainly no saint, I can't think of anything I've done that's bad enough to warrant someone pursuing defamation against me. (No doubt, there have been many occasions where I've been called an idiot or perhaps even a ratbag in private but I don't consider these amount to defamation.)

Nevertheless, I remain mindful that I could be wrongfully defamed in public for the very reason that others will remember the fact well into the future even though the claim was without merit.

Perhaps this is an evolutionary trait developed out of self-protection or similar, but whatever the underlying reason many remain mindful of the potential damage defamation can cause whether a claim is factual or not.

Incidentally, I know someone who committed a misdemeanor as a youth many decades ago and has been well behaved and kept out of trouble since. That said, on rare occasions someone will still mention the fact.

No doubt the right to have certain facts about oneself forgotten is a complicated matter, and if opinions were scaled just about everyone would have a different view—and, no doubt, those views would again vary according to one's perception of the claimed or actual wrongdoing (if plotted, I'd venture to suggest everyone's opinions would be a 3D graph and no two graphs would the same).

As the old parable goes 'try to please all and you'll please none'.

Yes. But I do not want to try to please all.

In case of doubt, for the (potential) victims.

I am dealing right now with a case, where a pedophile tries to sneak into some semi public group activity/festival I am part of. The most frustrating thing is exactly this, some people saying the past where he was convicted is gone (or the conviction wrong) and he changed. Except it isn't and he has not changed (I am certain of because of some things I have heard him say, which are sadly not recorded). And if the conviction would not exist officially anymore, I would have allmost nothing solid against him, that he is in fact not just some weirdo, but a dangerous weirdo who should not be welcome, where I go with my children.

edit:

"Let's assume your villain provides proof well beyond reasonable doubt that he has actually changed"

And if there is no doubt, there is no doubt. Then it would be fine. But I want to judge myself, with as many facts as I can get and not blindly trust. I know people can change. But if people hide their past, I assume they have not actually processed it.