If your argument is that people shouldn't be allowed to say things that harm the employment prospects of others, whether the accusation meets the threshold of criminal behaviour or not seems irrelevant. So why is crossing that threshold different? Why is it ok to say "We have evidence that this person did not turn up to the office" but not "We have evidence that this person engaged in sexual harassment"?

Because there's a significant difference between acusing someone of crimes and acusing someone of not being a diligent worker. And no, I'm not arguing that this is related to harming someone's employment prospects, but their reputation in general (which happens to encapsulate their employment prospects).

There are crimes I can be accused of that will enhance my reputation rather than diminish it. There are perfectly legal things I could be accused of that would destroy my career and my social relationships. If your argument is about reputational damage, then using criminality as the threshold for "It's not ok to make a public accusation" is entirely arbitrary.

FYI This is nonsensical, not even wrong, and relatively bizarre.

> I'll clarify my position: acusing someone of lawbreaking should not be permissible if you won't back yourself up in court.

That's an interesting position which you haven't presented much reasoning for; its not, however, what the US has generally decided, so if you want it to change, you should probably say why.

The decision the US has mostly come to is this:

(1) You can't impose legal sanction without proving something in court.

(2) If someone is harmed (including by accusation of criminal behavior) by something you say, they can challenge it in court as defamation (e.g., slander, libel). and they must show evidence that it is false.

Your proposal is a fairly radical restriction on free speech.