A grand jury is a common law jury; responsible for issuing indicts, examining evidence, and investigating alleged crimes. The grand jury can compel witnesses to testify. During the proceeding, the defendant and their counsel are generally not present. In some jurisdictions (which allow grand juries), defendants have the option of testifying before the grand jury. Most jurisdictions have abolished grand juries, replacing them with judges and evidentiary hearings; US jurisdictions are a notable exception.
The United States
Grand juries are required by the US federal government for "capital or infamous cases", according to the Constitution's Fifth amendment. Unlike with other provisions of the Bill of Rights, the Supreme Court has ruled that this requirement does not pertain to the regional state courts, and states are free to abolish grand juries.
Many US jurisdictions have replaced the grand jury with a procedure in which the prosecutor can issue charges, leading to a preliminary hearing.
Criticism of the Grand Jury
Some argue that the grand jury is unjust as the defendant is not represented by counsel and/or does not have the right to call witnesses.
In practice, a grand jury rarely acts in a manner contrary to the wishes of the prosecutor and as such many jurisdictions in the United States have replaced the formality of a grand jury with a procedure in which the prosecutor can issue charges by filing in information which is followed by a preliminary hearing before a judge at which both the defendant and his or her counsel are present.
In some jurisdictions, defendants have the option of testifying before the grand jury. Police officers who are accused of crimes in the course of their jobs, such as after the shooting of a suspect, sometimes take the opportunity to give the grand jury their side of the story. Grand juries in such situations frequently refuse to indict.