Regarding the determination of punishments, fans of game theory should find interesting the system of classical Athens. Here's a description from a lecture transcript:

If a penalty was called for, and it was not one that was described by law (and very few penalties were described by law), the following procedure was used: the plaintiff who had won the case proposed a penalty, [and] the defendant then had the opportunity to propose a different penalty. The jury then -- again no deliberation -- just voted to choose one or the other, but they could not propose anything of their own; no creative penalties were possible, just one or the other of the ones proposed by each side. Normally, this process led both sides, if you think about it, to suggest moderate penalties. For the jury would be put off by an unreasonable suggestion one way or another. If the plaintiff asked for too heavy a penalty that would guarantee they would take the other guy's penalty and vice versa.