Missouri prosecutors sometimes seek indictments by grand juries instead of felony informations by way of preliminary hearings. A prosecutor may choose whether to summon a grand jury to come to court and hear evidence and consider whether to issue an indictment, charging an accused with a crime. Criminal defense lawyers do not spend much time with grand juries because the proceedings are held in secret. Transcripts are generally not available. In most cases, prosecutors use a preliminary hearing and a judge decides whether a defendant should proceed to trial, saving grand jurors from having to come to court and saving taxpayers the expense of a grand jury. Also, preliminary hearings are generally not held in secret, so they have the benefit of a public hearing.
Grand juries have other duties, including investigations.
It shall be the duty of the grand jury, at each term, or a committee, to consist of at least three members thereof, to visit the jail of their county, and examine the condition thereof, and inquire into the treatment of the prisoners, and make report thereof to the court.
Missouri statutes governing grand juries are set forth in Chapter 540, RSMo. Grand juries have far more responsibility than to simply sit back and passively do what the prosecutor asks.