I think as a MJ fan, i know more about the US system, than the french one, unfortunately....
i think in both countries, there's nothing you can do about a criminal trial. Not even the victim can stop it (for ex Polanski). If the prosecutor wants to prosecute, he will (with certain limitations in both countries , grand juries/ preliminary hearing in the States- "judge of instruction" or however you would call that, but you know what I mean, In France. The role of this judge, in certain very serious cases, such as rape, or complicated cases, would be to oversee the investigation WITH ALL the parties involved, and then decide if you go to trial or not) .
I think the civil part comes right after a conviction in a criminal trial in France, so no conviction , no damages. I'm not sure, but I think it's the same procedure, you wouldn't have 2 trials, resulting in opposite outcome, such as OJ Simpson.
So MJ's situation in 93 would not have happend (settlement), and it makes it pretty shocking for uneducated French people.
I agree about punitive damages, I at least I have never heard that the damages allowed could depend on what you earn.