Under the Fifth Amendment of the U.S. Constitution, “no person shall be held to answer for a capital, or other infamous crime, unless on a presentment or indictment at a grand jury” in all felony prosecutions in federal courts. Thus, a person cannot be indicted (charged) with a crime in a federal court without a grand jury having first brought charges. Federal courts use regular grand juries and special grand juries. In the federal system, regular grand juries hear evidence and consider indictments submitted by a federal prosecutor to determine whether probable cause to charge the defendant exists. Special grand juries perform an investigatory function in federal criminal cases.
Most states (all but Connecticut and Pennsylvania and the District of Columbia) retain the option of a grand-jury indictment. Every state uses a grand jury for some function, although such use has diminished. Wisconsin, for example, has retained its grand-jury statute but has not actually convened a grand jury in at least 25 years.
State grand juries are generally made up of 6 to 23 people with a statutory term of service of up to one year, which is much longer than the typical term of service required by petit jurors (trial jurors). The scope of activities varies, but usually includes criminal indictments and investigations. Some states allow grand juries to take on other roles, such as investigating public officials and public buildings (particularly prisons), although this is rare. Some states provide for statewide grand juries to examine larger crime problems, such as drug distribution and gang violence.
Qualifications for grand jurors are generally the same as for petit jurors. For decision-making purposes, a majority is usually adequate, although some states establish a minimum number needed to indict.
There has been little study of the process, and very little data on performance exists. New York and Washington, D.C., established task forces to examine grand-jury use, and the ABA has published standards.
Grand juries remain controversial, particularly regarding the right to counsel during proceedings, whether witnesses must be informed when they are a target of investigation, and whether grand juries are necessary in today's justice system.
