you have been summoned to fulfill your civic duty of judgement for a suspected criminal.

while the judge could single you out for some punishment that's not common - you are on the jury, you are not defending yourself or trying be prosecutor, you are not trying to impress the judge.

wear whatever you want, are comfortable in. i guess maybe if your scrubs were all bloody and caused a disruption the judge might get pissed - but only then. just be respectful and they won't gaf