The law was changed a few weeks later to include private persons and sole traders as protected lsps, not just companies, but they had to convict me. No choice in the end.

I am not sure I would consider this "working well". It is the job of the court to determine if and how to apply law. Laws are never perfect and should be applied per intention, and not word-for-word. If the latter would even be possible, we wouldn't need judges in the first place, because it would be a "simple" decision tree. But it's not. And we have judges and the court processes for a reason.

If the law was amended a few weeks later, it shows, IMO, that the intention of the law was different than what was written down. Therefore the judge should have ruled that way by acknowledging that while the law does not exempt private individuals, its intention shows that it clearly should (simply because it doesn't make much sense otherwise).

In other words: if the system really worked well, the judge would have sentenced (or rather not sentenced) within the intention of the law, and not within the strict writing.

(Worst case is that something like that gets escalated to the highest court who then either also accepts or overrules it.)

Do they not have Jury Nullification over there?