Grand juries are usually thought to be for authorizing criminal prosecutions and to investigate public administration for evidence of misconduct. However, there is no limit to what a grand jury may consider, or on which it may report. This can be seen in the way legislative committees hold hearings to investigate problems with a view to developing or amending legislation. Essentially, a congressional hearing is a committee of Congress sitting as a grand jury. Various public commissions are also essentially grand juries by other names. We can list a few ways grand juries, perhaps by other names, might be used:
A grand jury could investigate, in response to specific citizen complaints, much as a legislative committee does, how well legislation is working, what else is needed, or whether it needs to be repealed. Enough reports tending to agree could move the legislative body to act on issues they might prefer to ignore.
A state grand jury could review state legislation and other actions for compliance with state and federal constitutions, and advance compliance in ways beyond the means of the citizen to pursue in the courts.
A federal grand jury could review the constitutionality of federal legislation or actions, and a finding of such to be unconstitutional might influence Congress and the courts without the complaining citizen having to pursue an expensive case all the way to the Supreme Court.
A state grand jury could review the constitutionality of federal legislation or actions, and if it found such to be unconstitutional, urge noncooperation with it by state officials and citizens, which could range from jury nullification to statewide civil disobedience that would, directly or indirectly, nullify the usurpation.
A grand jury could investigate complaints of judicial, prosecutorial, or other misconduct, and decide whether the officials were acting within their jurisdiction, for which they would have official immunity, or outside of it, for which they would not, thus authorizing civil or criminal prosecutions of the abusive officials.
A grand jury could examine whether an official of a public or private institution was acting within his authority, or had authority to hold his office, and if it finds there not to be sufficient evidence of such authority, authorize a jury trial on a writ of quo warranto or other such writ. This might be used where the judges are expected to be biased.
Grand juries might supervise the selection of trial juries and of other or succeeding grand juries, to insure they are not stacked.
If a grand jury, or even a trial jury, needed to be composed of persons with special skills, a grand jury could supervise a multistage selection process in which large numbers of citizens would first be selected at random, who would then select persons known to them to have special skills, from which a random selection might be made, and perhaps the alternating steps repeated until they get a panel of skilled but not biased or stacked members.
By a similar process of alternating random selection and evaluation of skills, a grand jury might select judges, prosecutors, or other public officials in a way that would avoid undue influence in their selection. They could even be set up within departments and organizations to select personnel for hiring, promotion, assignment, and termination.