Grand jury vs. trial jury: two panels, two very different jobs

A grand jury decides whether there is probable cause to bring a criminal charge. A trial jury, also called a petit jury, decides the verdict in a criminal case or the outcome of a civil case.

An indictment is a formal charge, not a finding that the accused person is guilty. The detailed comparison below is the federal-court baseline. State procedures can differ.

Grand jury vs. trial jury on the case timeline

1. Charging stage: A federal grand jury considers prosecutor-presented evidence and decides whether probable cause supports an indictment.
2. After an indictment: The person has been formally charged, not convicted.
3. Trial stage: A petit, or trial, jury decides the case. In a federal criminal trial, it decides whether the government proved the charge beyond a reasonable doubt.

The federal comparison

• Main job: A grand jury handles preliminary criminal matters. A petit jury decides criminal and civil cases.
• Result: A grand jury may issue an indictment. A criminal trial jury returns a guilty or not-guilty verdict. A civil trial jury finds for the plaintiff or defendant.
• Proof threshold: Federal grand juries assess probable cause. Federal criminal trial juries apply the beyond-a-reasonable-doubt standard. In federal civil cases, the plaintiff must prove the claim by a preponderance of the evidence, meaning more likely than not.
• Proceedings: Federal grand-jury proceedings are private and typically non-adversarial, with prosecutors and witnesses presenting evidence. Federal trials are generally public, while petit-jury deliberations are private.
• Panel and service: A federal grand jury has 16 to 23 members, considers multiple cases and generally serves up to 18 months. A judge can extend service to 24 months. A federal petit jury has six to 12 people, hears no more than one case and is then discharged.

Federal rules are not a national script

Massachusetts describes the same basic divide: grand jurors consider evidence presented by the prosecutor to decide whether it is sufficient to bring a criminal charge, and they do not decide guilt or innocence.

State grand-jury procedures can differ materially from federal practice. Some jurisdictions use a preliminary hearing before a judge instead of a grand jury in some cases.

Which label should you use?

Use grand jury for the pretrial criminal panel considering whether to indict. Use trial jury or petit jury for the panel that decides a criminal or civil case. In federal courts, “petit jury” and “trial jury” refer to the same type of jury.

Frequently asked questions

Does a grand jury indictment mean a person is guilty?

No. An indictment is a formal charge or accusation, not a finding of guilt. If a criminal case goes to trial, a trial jury decides whether the government proved the charge beyond a reasonable doubt.

Why are grand-jury proceedings private?

Federal grand-jury proceedings are private. Ohio-focused guidance identifies commonly stated reasons for secrecy, including protecting witnesses and jurors, encouraging candid testimony, avoiding alerting a potential defendant to an investigation, and reducing speculative accusations against people who are not indicted. Procedures and rationales can vary by jurisdiction.

Do all states use grand juries the same way as federal courts?

No. State grand-jury procedures can differ, and some jurisdictions use a preliminary hearing before a judge instead of a grand jury in some cases.

Sources

• Types of Juries - United States Courts — www.uscourts.gov
• What to know about federal grand juries | Pew Research Center — www.pewresearch.org
• Grand Jury Duty | Mass.gov — www.mass.gov
• Ohio Grand Juries FAQ - ACLU of Ohio — www.acluohio.org