Josh plays puppy:
I say blackmail should be illegal because innocent people can be unduly harassed and defamed by a blackmailer with fake evidence. Add to that the blackmailer faces no consequences.
Yes, because eliminating harassment and unpleasantry is a proper responsibility of the government, right? No doubt that’s why the government schools are so uniformly civil and enjoyable. Josh is chasing his own tail here, because if a blackmailer presents fake evidence, he has committed fraud and is liable for facing the consequences of any damages caused by that fraud.
Take Nick B’s much-feared situation of the grope-and-flash. False evidence such as this necessarily features actual evidence behind it. The person being blackmailed has the option of suing the blackmailer, who would have to present a woman to testify in court that she was in fact having an affair with the innocent victim. Would it be possible for him to convince her to lie? Sure, but now we are piling improbabilities on top of absurdities, which should suffice to demonstrate to everyone what an incredibly stupid basis for law this would be.
I assert that the technology argument is not only hypothetical at this point, but also indicates that what is today considered “proof” will likely not be considered proof tomorrow.