A grand jury is a group of ordinary citizens who meet in private to review a prosecutor’s evidence and decide whether there is enough reason to formally charge someone with a serious crime. It does not decide guilt. Its single job is to answer one question: is there probable cause to believe a crime occurred and that a particular person committed it? If the answer is yes, the grand jury issues an indictment, and the case moves toward trial. If not, the prosecution stalls before a courtroom is ever involved.
The Fifth Amendment requires a grand jury indictment before the federal government can prosecute anyone for a serious criminal offense. Roughly half the states impose a similar requirement for at least some felonies; the rest let prosecutors file charges a different way.
How a Grand Jury Differs From a Trial Jury
People often mix the two up, and the differences matter. A trial jury (sometimes called a petit jury) sits in open court, hears both sides, and delivers a verdict of guilty or not guilty. A grand jury sits in a closed room, hears only the prosecutor’s side, and decides whether charges should be brought at all. No judge is present during a grand jury’s work.
The numbers are different too. Federal trial juries have 6 to 12 members and generally must reach a unanimous verdict. Federal grand juries seat 16 to 23 members, and an indictment requires 12 votes in favor, with at least 16 jurors present when the vote is taken.1United States Courts. Handbook for Federal Grand Jurors The lower threshold fits the limited role: the grand jury is not convicting anyone, just deciding whether the evidence is strong enough to justify putting the case in front of a trial jury.
What Happens Inside the Grand Jury Room
Grand jury proceedings are one-sided by design. The prosecutor presents evidence, calls witnesses, and explains the applicable law. The person under investigation is almost never present, and defense attorneys play no role in the room. This is the feature critics focus on most: the grand jury hears only what the prosecutor chooses to show it.
The evidence rules are far looser than at trial. Grand juries can consider hearsay and other material that would be excluded from a courtroom. The Supreme Court confirmed this in Costello v. United States (1956), holding that an indictment based entirely on hearsay is valid. The reasoning is practical: the grand jury is screening for probable cause, not deciding guilt.
While a witness is testifying, only a small group may be in the room: the grand jurors, the prosecutor, the witness, a court reporter, and an interpreter if one is needed.2Legal Information Institute. Federal Rules of Criminal Procedure Rule 6 – The Grand Jury When the jurors deliberate and vote, everyone else leaves.
Why It All Happens in Secret
Secrecy is one of the grand jury’s defining features. Federal Rule of Criminal Procedure 6(e) bars grand jurors, prosecutors, court reporters, and interpreters from disclosing what happens inside the room.2Legal Information Institute. Federal Rules of Criminal Procedure Rule 6 – The Grand Jury The policy serves several purposes: it protects people who are investigated but never charged from public stigma, encourages witnesses to testify honestly without fear of retaliation, and prevents targets from learning about the investigation and either fleeing or tampering with evidence.
Witnesses themselves are not bound by the rule. A witness who testifies before a grand jury is free to discuss their own testimony with anyone afterward. The secrecy obligation falls on the institution, not on every person who walks through the door.
Rule 6(e)(3) does allow disclosure in limited circumstances: to government attorneys and personnel assisting a federal criminal investigation, to state officials when the material may reveal a state crime, to a separate federal grand jury, and under a court order when a party shows a “particularized need” tied to a judicial proceeding. Each exception requires either a court order or a specific statutory basis.
What the Vote Produces
When the prosecutor finishes presenting evidence, the grand jury votes. If the required number of jurors find probable cause, the grand jury returns an indictment, historically called a “true bill.” That document is the formal criminal charge that sends the case to trial.1United States Courts. Handbook for Federal Grand Jurors
If the grand jury finds the evidence insufficient, it returns a “no bill,” and the prosecution cannot move forward on that indictment. A no bill is not an acquittal. The prosecutor can gather more evidence and bring the case to a different grand jury later, because the person was never “in jeopardy” in the trial sense.
Where Grand Juries Are Actually Used
The Fifth Amendment’s grand jury requirement applies only to the federal government. The Supreme Court held in Hurtado v. California (1884) that states are not bound by the grand jury clause, and that holding has never been overturned.3Justia Law. Hurtado v California, 110 US 516 (1884) States are free to charge felonies without a grand jury, and many do.
About half the states require grand jury indictments for at least some serious crimes. The rest let prosecutors file charges through a document called an “information,” which a judge then reviews at a preliminary hearing. A preliminary hearing is the opposite of a grand jury proceeding in one important respect: the defense is in the room, can see the prosecution’s evidence, and can cross-examine witnesses. Some states give prosecutors the choice between the two, and prosecutors often prefer the grand jury because the defense is not there.
If You Get Called as a Witness
People involved in a grand jury investigation fall into three categories. A “witness” has relevant information. A “subject” is someone whose conduct is within the scope of the investigation. A “target” is the person the prosecutor expects to indict. The label affects how the government treats you and what protections come into play.
Every person called to testify before a grand jury is protected by the Fifth Amendment privilege against self-incrimination.4Legal Information Institute. Fifth Amendment You can refuse to answer any question whose answer might expose you to criminal liability. You have to invoke the privilege question by question while testifying, though. You cannot announce a blanket refusal and walk out.
One thing surprises most people: your attorney cannot come into the grand jury room with you. Rule 6 limits who may be present during testimony to the jurors, the prosecutor, the witness, a court reporter, and an interpreter.2Legal Information Institute. Federal Rules of Criminal Procedure Rule 6 – The Grand Jury Your lawyer waits in the hallway. You do have the right to step outside and consult with them before answering any question, and grand jurors are instructed not to draw negative conclusions from a witness who does this repeatedly.
If you are a target, federal prosecutors are generally expected to notify you of that status before you appear. Under Department of Justice policy, a target who submits a signed written statement from both the target and their attorney declaring they will invoke the Fifth Amendment is ordinarily excused from testifying, unless the grand jury and the U.S. Attorney agree the appearance is still necessary.5United States Department of Justice. Justice Manual 9-11.000 – Grand Jury This is internal DOJ policy, not a constitutional right, so the rules can differ in a state grand jury.
The Fifth Amendment lets you stay silent, but the government has a tool to take that option away: an immunity order. A prosecutor can obtain a court order granting you immunity, after which you lose the right to refuse on self-incrimination grounds. Federal immunity is “use immunity,” meaning nothing you say and no evidence derived from your compelled testimony can be used against you later, though the government can still prosecute you with independently obtained evidence. Lying under oath is the one way immunized testimony can come back on you, through a perjury charge.6Office of the Law Revision Counsel. 18 USC 6002 – Immunity Generally
What Happens If You Ignore a Subpoena
A grand jury subpoena is a court order, not a polite invitation. Ignoring one, or showing up but refusing to answer questions without a valid legal basis like the Fifth Amendment privilege, exposes you to civil contempt. A federal court can order you confined until you agree to comply, and that confinement can last up to 18 months.7Office of the Law Revision Counsel. 28 USC 1826 – Recalcitrant Witnesses
The 18-month cap exists because civil contempt is meant to coerce compliance, not to punish. Once the grand jury’s term expires, the legal basis for holding you disappears. A witness who deliberately avoids service or defies a subpoena may also face separate criminal contempt proceedings, which carry their own penalties.