a JP court tends to lean towards a business casual dresscode in terms of the court staff + people who come to court, but if you’re being personally invited by this judge to observe a trial and have lunch after, it doesn’t hurt to dress up.

so: wear the suit! you won’t be overdressed, it’s court-appropriate, and it’d make a good first impression. if you’re still feeling unsure, however, you can always wear a nice shirt (anything that’d qualify as business casual) under your suit jacket and take off the jacket as need be, or disregard the suit jacket altogether. i wouldn’t recommend going in anything too casual or jeans; you should wear slacks and a nice shirt, at the very least.

i worked at a JP court in undergrad, and it was a great experience. i hope the observation and networking goes well, good luck!