The grand jury plays an important role in the criminal process, but not one that involves a finding of guilt or punishment of a party. Instead, a prosecutor will work with a grand jury to decide whether to bring criminal charges or an indictment against a potential defendant -- usually reserved for serious felonies. Grand jury members may be called for jury duty for months at a time, but need only appear in court for a few days out of every month. Regular court trial juries are usually 6 or 12 people, but in the federal system, a grand jury can be 16 to 23 people. The grand jury is one of the first procedures in a criminal trial. Courts often use preliminary hearings prior to criminal trials, instead of grand juries, which are adversarial in nature. As with grand juries, preliminary hearings are meant to determine whether there is enough evidence, or probable cause, to indict a criminal suspect. Unlike a grand jury, a preliminary hearing is usually open to the public and involves lawyers and a judge (not so with grand juries, other than the prosecutor). Sometimes, a preliminary hearing proceeds a grand jury. One of the biggest differences between the two is the requirement that a defendant request a preliminary hearing, although the court may decline a request.…