⟩ Explain me how your legal organisation/law firm defines success?
It would be wise to save this question for the interviewing manager, and not for a peer/technical discussion. Nobody likes a kiss-up, but letting management know that you will communicate openly and honestly with them, always scores big points. The last part of the question can be a good barometer about how easy it will be to become a top performer. You can follow up with a discussion of how you have been successful in your previous jobs.