I interviewed with two Federal District Court Judges. One I interviewed with just the Judge, and it was much like a 30 minute firm interview with questions like "what do you do for fun" ect. My second interview (for a different Judge), I only interviewed with the clerks. I got a lot harder questions like "what do you think you would do here", "whats your approach to research" and "whats the biggest area in your research that can be improved." I would also be prepared for the standard "why do you want this job" ect. Good luck! (PS - I start with my externship on Monday, and Im even more nervous about starting!)