Definition - What does Bar mean?
The bar refers to the railing or banister that divides the sections of a courtroom. On one side of the bar are spectators and members of the public. On the other side are the judges, lawyers, witnesses and jury.
Justipedia explains Bar
When a trial is going on, spectators are supposed to stay behind the bar. If they do not respect this rule, they can be held in contempt of court. The bar is essentially the area where the lawyers and judges do their work.