I think they should be somehow restricted to using non-generative models (or at least for the user facing output). Something that would only identify potentially relevant case law from an existing set, to accelerate the search process.

Common law in general seems essentially impossible to formalize in such a way to use purely deterministic reasoning models of yesteryear, but I'm sure many specific laws could be converted, especially in fields like tax law (I'm sure they already are by many big players)