Re: Question for you folks

Possession continues happening as long as you, well, possess the stuff. It would be argued that you are being prosecuted not for possessing it when it was legal, but for possessing it today. Same as has happened with some gun laws, in the US and beyond. And there was a short period during which you were supposed to destroy it all or turn it in to have the authorities do it (which of course, they didn't), free of prosecution.

Which is one big reason why possession laws (and I don't just mean this, I mean every law that criminalizes possession of anything at all) should never be allowed to exist. There must be some legitimate ban somewhere (I haven't found it, though), but I don't see why you cannot criminalize production, trade, distribution, purchase or acquisition but leave possession alone. Obviously if you are in possession of something either you bought it, or were given it, or borrowed it, or stole it: any of which can easily be criminalized without creating physical paradoxes.