"Dress for where you're going, not where you've been" is another one of the timeless gems learned from my old boss in New York. It means to look as good as you want your future to look. Or as my mom would say, Don't dress like a bum unless you want to be one.
Showing up at a court proceeding is more than just showing up, even if you have a good lawyer (like Sanderson Law, P.C.) doing all the talking. Being on time (a little early is on time), cleaned up, dressed up, and positive, sends valuable messages to the other side, to people watching, and to the judge. It conveys commitment to toughing out the process and confidence in the outcome.
Business casual is the baseline. Anything more is better. Although they say you can never be too dressed up (people assume you're going someplace better later), don't overdo it - leave the flashy tuxedo or evening gown for the party when the case is finished. How you look in court says a lot, so make it the best you can say.