How Grand Juries Work in the U.S. Justice System
Understand the purpose, powers, and limits of grand juries, from investigations and indictments to secrecy and citizen participation.
In the United States criminal justice system, a grand jury is a group of citizens called together to decide whether there is enough evidence to formally charge a person with a crime. Unlike a trial jury, a grand jury does not decide guilt or innocence; it focuses on whether there is probable cause to move a case forward to trial.
Grand juries play a powerful gatekeeping role: they investigate potential criminal conduct, review evidence presented by prosecutors, and decide whether to issue an indictment that starts a felony prosecution.
What Is a Grand Jury?
A grand jury is a body of citizens selected from the community to review evidence in criminal matters before a case reaches trial. In federal court and in many states, grand juries are used primarily for serious offenses, especially felonies.
- Size: Typically 16–23 jurors in federal cases.
- Term of service: Often several months and, in the federal system, up to 18 months, with possible extension.
- Role: Decide whether there is probable cause to believe a crime was committed and that a particular person committed it.
- Setting: Proceedings are conducted in private, not in open court.
Grand juries sit as a preliminary screening body. If they find the evidence adequate, they return an indictment. If not, they decline to charge, sometimes called a “no-bill.”
Grand Jury vs. Trial Jury: Key Differences
Grand juries and trial (or “petit”) juries are both central to the American jury system, but they serve different purposes and operate under very different rules.
| Feature | Grand Jury | Trial Jury (Petit Jury) |
|---|---|---|
| Main function | Decide whether to charge (indict) based on probable cause | Decide guilt or innocence (criminal) or liability (civil) |
| Number of jurors | Usually 16–23 members in federal system | Usually 6–12 jurors, depending on jurisdiction |
| Standard of proof | Probable cause that a crime was committed and the suspect committed it | Beyond a reasonable doubt in criminal cases |
| Proceedings | Private and one-sided; prosecutor leads, judge rarely present | Public, adversarial; both prosecution and defense present cases |
| Defendant’s presence | Usually absent; may appear only under limited circumstances | Always present, with attorney |
| Outcome | Indictment (true bill) or no-bill | Verdict: guilty or not guilty (criminal) |
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Constitutional and Legal Basis for Grand Juries
The concept of a grand jury comes from English common law and was adopted into American practice during the colonial period.
- Fifth Amendment: The U.S. Constitution states that no person shall be held to answer for a serious federal crime unless on a presentment or indictment of a grand jury, with limited exceptions (such as military cases in wartime).
- Federal rules: Federal grand juries are governed by the Federal Rules of Criminal Procedure, especially Rule 6 (grand jury) and Rule 17 (subpoenas).
- State practice: Many states use grand juries for serious crimes, while others rely more heavily on preliminary hearings before a judge. Procedures and requirements vary by state.
In some jurisdictions, a defendant can waive the right to grand jury review and have a judge determine probable cause instead, though this is less common in serious felony cases.
Core Functions of a Grand Jury
Grand juries serve two broad functions in criminal procedure:
- Investigative function
- Charging (accusatory) function
Investigative Function
As an investigative body, a grand jury has broad authority to gather information about possible criminal conduct.
- Review documents, records, and physical evidence.
- Hear sworn testimony from witnesses.
- Issue subpoenas compelling production of evidence or a witness’s appearance.
- Request assistance from prosecutors in obtaining additional information.
This investigative power can be used even before a specific person is formally identified as the target of an investigation.
Charging Function
In its charging capacity, the grand jury decides whether there is enough evidence to formally accuse someone of a crime.
- If the requisite number of jurors agree there is probable cause, they return an indictment (often called a “true bill”).
- If they find the evidence insufficient, they return a no-bill or dismiss the proposed charges.
An indictment is not a conviction. It is a formal accusation that starts the criminal case in court, where a separate judge and, often, a trial jury will decide guilt or innocence under the higher “beyond a reasonable doubt” standard.
How Grand Jury Proceedings Typically Work
Grand jury sessions follow a fairly consistent pattern, though details vary by jurisdiction and by the nature of the investigation.
1. Impaneling the Grand Jury
Grand jurors are selected from the same general pool as trial jurors. The court screens potential jurors for eligibility, including lawful residence, language ability, and lack of disqualifying criminal history, similar to petit jury criteria.
- Jurors take an oath to perform their duties honestly and maintain secrecy.
- A foreperson is chosen to help manage proceedings and sign indictments.
2. Presentation of Evidence
Once seated, the grand jury hears evidence in cases selected by prosecutors:
- The prosecutor presents witnesses, documents, and other evidence.
- Witnesses testify under oath and may be questioned by both the prosecutor and jurors.
- Jurors may request additional witnesses or documents through the prosecutor or by issuing subpoenas.
The suspect (sometimes called the “target” or “subject”) usually does not attend and has no right to present evidence, unless invited or allowed under local rules.
3. Instructions on the Law
Before voting, grand jurors receive legal instructions about the elements of the offenses and the standard of probable cause. In federal practice and in many states, the prosecutor explains the law; a judge is not typically present in the grand jury room.
4. Deliberation and Vote
After the evidence is presented, the grand jury deliberates in private, without the prosecutor or any other non-juror present.
- A minimum number of jurors must be present to deliberate and vote; federal rules require a quorum out of the 16–23 members.
- At least 12 jurors must usually vote in favor of indictment for it to be returned in federal court and in many states.
If the required number agree that probable cause exists, the foreperson signs the indictment, which is then presented to the court. If not, no charges are filed from that proceeding.
The Principle of Grand Jury Secrecy
Grand jury proceedings are conducted in secret, a defining feature of the institution.
Reasons for secrecy commonly include:
- Encouraging witnesses to speak freely without fear of public exposure or retaliation.
- Protecting the reputations of individuals who are investigated but never charged.
- Preventing suspects from fleeing, tampering with evidence, or coordinating stories.
- Allowing jurors to deliberate without outside pressure.
In most jurisdictions, jurors, prosecutors, and court staff are prohibited from disclosing what occurs in the grand jury room, except under narrow legal exceptions, such as court-ordered disclosure in later proceedings.
Rights and Roles of Key Participants
Prosecutor
The prosecutor leads the presentation of cases before the grand jury. In federal practice, prosecutors have an obligation under Department of Justice policy to present substantial evidence that directly negates the guilt of a target when they are aware of it, even though grand jury proceedings are one-sided.
Witnesses
Witnesses may be law enforcement officers, experts, or private individuals who have information relevant to the investigation.
- They are sworn to tell the truth and may be subject to perjury charges if they lie.
- They can assert privileges, such as the Fifth Amendment privilege against self-incrimination.
- In many jurisdictions, witnesses may consult with their attorneys outside the grand jury room, but counsel usually may not be present while they testify.
Target or Subject of the Investigation
The person under investigation usually has limited involvement at the grand jury stage:
- No right to attend proceedings.
- No right to present evidence directly, unless permitted.
- No right to cross-examine witnesses.
However, defense counsel can often communicate with the prosecutor, submit written materials, or request that exculpatory evidence be presented.
Grand Jurors
Grand jurors are not passive observers. They may ask questions, request additional evidence, and vote independently of the prosecutor’s preferences.
- They must base decisions on the evidence and the law as instructed.
- They may refuse to indict if they believe the evidence is legally insufficient or the case is unjust.
When Is a Grand Jury Required?
Whether a grand jury is required depends on the jurisdiction and the seriousness of the offense:
- Federal felony charges: The Fifth Amendment generally requires a grand jury indictment for serious federal crimes, unless the defendant waives that right.
- State crimes: Some states require grand jury indictments for certain felonies; others use them selectively or allow prosecutors to file charges directly and rely on preliminary hearings.
- Misdemeanors: Minor offenses rarely go through a grand jury; they are typically charged by complaint or information.
Advantages and Criticisms of Grand Juries
Potential Benefits
- Citizen oversight: Brings community judgment into the early charging decision, rather than leaving it solely to prosecutors or judges.
- Protection from unfounded charges: Intended to shield individuals from baseless or politically motivated prosecutions by requiring group agreement on probable cause.
- Investigative flexibility: Powerful subpoena tools can uncover complex or organized criminal activity.
Common Criticisms
- Prosecutor dominance: Because proceedings are one-sided and defendants lack representation, critics argue grand juries often follow the prosecutor’s lead.
- Limited transparency: Secrecy, while serving important purposes, can make it difficult for the public to evaluate controversial decisions.
- Inconsistent use across states: Different rules and practices can lead to varying levels of protection and oversight.
Practical Takeaways for Defendants and Witnesses
If You Are Under Investigation
If you learn that you are a target or subject of a grand jury investigation:
- Consult an experienced criminal defense attorney promptly.
- Do not ignore subpoenas; failing to comply may lead to contempt proceedings.
- Discuss with counsel whether to assert your Fifth Amendment rights or provide information.
- Understand that an indictment is not a conviction but does begin a formal criminal case.
If You Are Called as a Witness
Witnesses also face serious obligations and potential risks:
- Tell the truth; false statements under oath can lead to perjury charges.
- Ask about your status (witness, subject, or target) so you and your attorney can evaluate your risk.
- Assert applicable privileges when appropriate, ideally with legal advice.
Frequently Asked Questions About Grand Juries
Do all criminal cases go through a grand jury?
No. Grand juries are typically used for serious federal crimes and, in some states, serious felonies. Many state-level cases, especially misdemeanors, are charged by complaint or information without grand jury involvement.
Can a defendant challenge a grand jury indictment?
Defendants can sometimes file motions to dismiss indictments—for example, if the grand jury was improperly selected or if serious legal errors occurred—but courts are often reluctant to second-guess grand jury decisions absent clear violations of law.
Are grand jury decisions final?
A grand jury’s decision to indict starts a criminal case; it does not determine guilt. A decision not to indict generally ends that particular proceeding, but prosecutors may sometimes present additional evidence to a new grand jury if the law allows.
Can someone serve on both a grand jury and a trial jury in the same case?
Jurisdictions typically prevent a person who served on a grand jury in a specific case from sitting on the trial jury for that same case, to avoid bias and preserve fairness.
Why is the target not allowed in the grand jury room?
The grand jury is designed as an investigative and screening body, not an adversarial forum. Limiting participation to prosecutors, jurors, witnesses, and essential staff helps preserve secrecy, protect witnesses, and prevent interference with the investigation.
References
- Types of Juries — United States Courts. 2024-01-01. https://www.uscourts.gov/court-programs/jury-service/types-juries
- Grand Jury — Legal Information Institute, Cornell Law School. 2023-01-01. https://www.law.cornell.edu/wex/grand_jury
- 9-11.000 – Grand Jury — United States Department of Justice, Justice Manual. 2020-12-01. https://www.justice.gov/jm/jm-9-11000-grand-jury
- Grand Jury — Wikipedia (background only; not cited for specific facts). 2024-01-01. https://en.wikipedia.org/wiki/Grand_jury
- Grand Juror’s Handbook — New York State Unified Court System. 2019-01-01. https://nyjuror.gov/pdfs/hb_Grand.pdf
- What, Exactly, Is a Grand Jury? — MoloLamken LLP. 2021-06-01. https://www.mololamken.com/knowledge-What-Exactly-Is-a-Grand-Jury
- Overview of the Grand Jury System — Supreme Court of Ohio. 2016-02-01. https://www.supremecourt.ohio.gov/Boards/grandJury/Materials/2016/Feb/grandJuryOverview.pdf
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