The grand jury system was established to be a promoter of justice and fairness. This system was formulated not only for the purpose of facilitating the prosecution of offenses, but also to afford protection to those who are being prosecuted for offenses that they have allegedly committed. Under the grand jury system, a case is not automatically brought before the trial courts. Instead, the case would have to be first presented to the grand jury for determination of whether or not probable cause exists that would justify placing the accused under trial.
The primary function of the modern grand jury is to review the evidence presented by the prosecutor and determine whether there is probable cause to return an indictment (“Frequently Asked Questions”). By means of this kind of system, it was believed that justice will be better served because only the right persons for the right offenses will be prosecuted. In establishing this kind of system, it was hoped that prosecution would be more effective and concomitant to the concept of fair play.
Instead of allowing the prosecutor to decide solely whether a particular case should be the subject of a full-blown trial or hearing, a body will be given the duty of considering whether a considerable amount of evidence was presented in order to justly conclude that probable exists for purposes of bringing the matter before the courts. True enough, in allowing a body like the grand jury to perform this task would prevent undue biases from interfering in the administration of justice.
There are, however, points that have been raised criticizing this theory. It has been said that the grand jury system does not really share the same amount of discretion given to prosecutors when it comes to prosecuting offenses and offenders. To a certain extent or degree, the probability of a case going to court is till left to the discretion of the prosecutor. As pointed out, The grand jury hears only cases brought to it by the prosecutor. The prosecutor decides which witnesses to call. The prosecutor decides which witnesses will receive immunity.
The basic questioning is done by the prosecutor on a theory he or she articulates. The grand jury members are generally permitted to ask questions at the end of a witness's testimony. The prosecutor generally decides if he or she has enough evidence to seek an indictment. Occasionally the grand jurors may be asked whether they would like to hear any additional witnesses, but since their job is only to judge what the prosecutor has produced, they rarely ask to do so (“Frequently Asked Questions”).
It must be noted, however, that the role of the grand jury is not to be as substitute for the prosecutor. The grand jury was established in order to maintain a balance in deciding whether or not a case should proceed to trial. The system of checks and balances has often been used to describe the role of the grand jury system vis-a vis that of the prosecutor.