Legal Question in Criminal Law in California

Probably not, but you haven't provided enough information to answer with any degree of confidence. In particular, it's not clear what you mean by "involved." Is the person involved as a party, a lawyer, or something else? Is your son being sued by same entity you sued? What is the lawsuit about? What was your lawsuit about? Was your son a party to that suit. How long ago did that case end?

Cases sometimes present a conflict of interests for a lawyer, but conflicts for a party are rare. Conflicts for close relatives of a party or lawyer are rarer still. Being a close relative, by itself, would not be enough. After all, your son is your close relative and you don't concerned about a conflict from that relationship.

Offhand, it's hard to think of a situation where a relative could have a conflict. It's not even clear that you are using the word "conflict" the same way lawyers use it. As I said, I would need to know more about the two cases before I could give you any meaningful guidance.