Any demands proper etiquette during a hearing. Neither side will benefit from a hearing where both parties throw harsh language at each other or argue in loud voices. You can't even laugh in a courtroom. Case in point: in 2010, a man in Fayetteville was charged with a misdemeanor after laughing at the courtroom for reasons he refused to say.
Disorderly conduct can have a serious implication on the outcome of your case. When the bailiff says “All rise” as soon as the judge enters the court, stand up. Lawyers say the action is meant for honoring the sanctity of the courtroom.
By the way, anyone can be ordered out of the courtroom if they're becoming a nuisance to the trial; not just the plaintiff and defendant. Even the small audience behind them can be ordered to leave the courtroom if they exhibit disorderly conduct, such as booing.
Courtrooms also enforce a strict dress code; wear clothes as if you're going to mass on a Sunday. In some cases, it's not advisable to wear shirts and clothing that depict anti-government or illicit themes. If you're confused about the varying courtroom rules by state, assume that these rules also apply to your state.