Above All, Dress Respectfully
You want to let the judge know the minute he or she sees you that you take this situation seriously. Don't just dress as if you're going to church or synagogue. Dress as if you're going to your MOTHER's church or synagogue. Wear clothes that are modest, clean and which fit you well. Clothes don't have to be new but they should demonstrate that you understand that this is a serious occasion.
Don't Dress to Distract
If this court appearance is about something that is important to you (and it should be, why else would you be there?), you don't want your appearance to divert the judge's attention from your message. Wear clothes that are simple, tailored, neutrally-colored (with a few exceptions) and allow any focus on you to be about your message, not about your appearance.
Should I Dress Like a Lawyer?
Probably not....unless you actually are a lawyer. Otherwise, it's OK to dress like a civilian. You don't want the judge to think you're playing "dress up" and pretending to be a lawyer. That could be perceived as arrogance, which you want to avoid.
For the Guys...What NOT to Wear.
Starting from the top, unless you wear something on your head for religious purposes no hats or caps. Court staff will probably make you take it off anyway. No dark glasses (like sunglasses) unless you have a medical reason to wear them. Minimal jewelry. If you wear earrings, take them out or wear a small stud. NO bling! Expensive jewelry also says, "I've got plenty of money to give away here." If you wear contacts but own glasses, wear the glasses. Got long hair? In addition to coming in as freshly washed as possible, if you're not going to cut it, wear it back in a ponytail. Long-sleeve shirt and tie with sports coat and slacks. NO jeans. Need I say that it is NEVER OK to wear pants so low a judge can see your underwear? It's also OK to wear a long-sleeve shirt with a pull-over sweater and slacks. Shoes: dress shoes or loafers. Polished. No tennies, sandals or flip-flops. If you have tattoos, do your best to cover them. They are a distraction (see step 2).
For the Gals...What NOT to Wear
Again, we start at the top. Hair should be clean and simple. No hats unless for religious reasons. Make-up should be minimal. Foundation, mascara, lip gloss in a neutral color. No dark glasses ( regular glasses or contacts are both fine). Minimal jewelry and what you wear should be small and tasteful. Dress or skirt and top are fine. They should not be form-fitting (no matter what a great body you have...this is not a place to get a date, it's a courtroom). Length should be about knee length. Slacks or a pants suit are also fine (not jeans, not leggings). Sweater or sweater set and skirt or slacks are fine. NOTHING low-cut in the front. NO sleeveless tops (Michelle Obama's great arms not withstanding, this is not the place for it.) If you wear a skirt or dress, where pantyhose. Dar or neutral are fine. Shoes should be flats or low (no more than 2") heels. They should be in good, polished shape. Remember what I told the guys about tattoos? Same goes for you.
When In Doubt.....
If you have a lawyer, tell your lawyer what you're planning to wear and ASK your lawyer if that sounds OK. Your lawyer will appreciate it since it's one less thing to worry about and the lawyer can then focus on your case. If you have no lawyer take a field trip to the courtroom where your case is going to be heard. Take a look around the room and see who seems "dressed for success" there. Pay attention to how the judge responds to people as they come before him or her. Your case many not be won based on how well you dress but you sure don't want your case lost for that reason, either!