Legal Beagle by Graeme Edgeler

If there's a bill proposing to change hate speech laws, would it be possible to have a section added that applies penalties based on speech that occurred (including in Parliament) before the change, but only applies to those MPs whose votes were cast in favour of the third reading? You might want to exempt things the MPs said before they turned 18, and maybe even things they'd apologized for before the third reading or (if they didn't remember the offence at that time) as soon as it came to their attention.

I feel that something like this would concentrate the minds of those MPs supporting the change and encourage clarity in the law, even if the main effect of the law change is going to be greater scrutiny of what may have already been illegal (or close enough to illegal to be investigated).