Legal Question in Insurance Law in California

If doing so violates any law or court order, maybe. If it is truly yours and not a mistake, why would you even ask the question? There obviously is more to what you asked.

You are entitled to cash any check made out to you only, but that doesn't mean you get to keep the money without going to jail. If it's not your money, or you are obligated to do something with it that you don't do, sure, you could go to jail.