What does that imply? We can always alter the rules of an expert system or add new rules.

[Edit:] i am referring to civil law legal systems, not civil law in common law systems. Precedents count very little in the former.

Annnnnnnd who will come up with these rules?

Edit for your edit: civil law still has to be constantly amended.

The main difference is that civil systems unifies the judicial and legislative functions under the premise that it can all somehow be decided in advance for every case.

Well, to answer your question, humans will come up with these laws (through legislative action or sth, IANAL). An expert system wouldn't need to record its previous decisions since it can come up with them when needed. In this sense it can be more adaptible than common law courts.