How Grand Juries Work: Secret Proceedings and the Path to Indictment
A grand jury is not a trial jury in miniature. It meets behind closed doors, hears only the prosecution's side, and decides a single narrow question: is there enough evidence to formally accuse someone of a crime. That low bar, combined with total secrecy, makes the grand jury one of the least understood parts of the criminal justice system.
Published July 6, 2026A Screening Body, Not a Verdict
The grand jury's job ends the moment it decides whether probable cause exists to believe a crime was committed and that the accused committed it. It does not determine guilt, does not weigh a defense, and does not sentence anyone. If it votes to charge, it returns what is called a true bill, formalized as an indictment; if it declines, the result is a “no bill,” and the prosecutor typically cannot refile the same charge before that same grand jury, though the case is not always dead — prosecutors can sometimes bring it to a different grand jury or proceed by other means depending on the jurisdiction.
The Fifth Amendment requires grand jury indictment for federal felony charges: “No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury.” That requirement has never been extended to the states through the Fourteenth Amendment, which is why roughly half of U.S. states let prosecutors file felony charges directly through a document called an information, skipping the grand jury for most cases and using a preliminary hearing before a judge instead.
Composition and How Jurors Are Chosen
Federal grand juries are larger than trial juries — 16 to 23 members — and require the concurrence of at least 12 to indict. State practice varies, with some states using panels as small as seven. Jurors are drawn from the same source lists used for trial juries, typically voter registration and driver's license records, and serve for an extended term, often 18 months to two years, hearing multiple unrelated cases rather than a single trial.
Why the Prosecutor Controls the Room
Defense attorneys are not present in the grand jury room. Neither is a judge. The proceeding is run entirely by the prosecutor, who presents evidence, questions witnesses, and gives the jurors legal instructions on the elements of the crime under consideration. A target of the investigation can sometimes be invited to testify but has no right to bring a lawyer into the room, cannot cross-examine witnesses, and cannot present a competing version of events through counsel. This one-sided structure is the source of a well-worn line, attributed to a New York chief judge, that a prosecutor could get a grand jury to “indict a ham sandwich” — a comment about how heavily the process favors the state, not a literal claim about the food.
The evidentiary standard reinforces the imbalance. A grand jury applies a probable cause standard — a reasonable belief that a crime occurred — which is far lower than the “beyond a reasonable doubt” standard a trial jury must apply to convict. Hearsay, evidence that would often be excluded at trial, is generally admissible in grand jury proceedings, and grand juries almost always vote to indict when a prosecutor asks them to.
Secrecy Rules and Why They Exist
Federal Rule of Criminal Procedure 6(e) imposes strict secrecy on grand jury proceedings, barring prosecutors, court reporters, and jurors themselves from disclosing what happened in the room, with narrow exceptions for judicial proceedings. The justifications, laid out by courts repeatedly, include protecting the reputation of people who are investigated but never charged, preventing suspects from fleeing or tampering with evidence once they learn an investigation is underway, encouraging witnesses to speak candidly without fear of retaliation, and shielding jurors themselves from outside pressure. Violating grand jury secrecy can result in contempt of court, which is why leaks from federal grand jury proceedings are relatively rare compared to other stages of a criminal case.
Investigative Power Beyond Individual Charges
Grand juries also serve an investigative function separate from screening a specific charge. A grand jury can issue subpoenas compelling testimony or the production of documents, giving prosecutors a legal tool to gather evidence that would otherwise require a court order through other channels. Special grand juries, empaneled for extended terms specifically to investigate organized crime, public corruption, or other complex matters, can issue reports as well as indictments, and some jurisdictions allow them to recommend systemic reforms even when no individual is charged.
How This Fits the Larger System
The grand jury sits at the very front of a process that continues through arraignment, pretrial motions, and either a plea or a trial. Its low threshold and one-sided procedure exist because the framers wanted a check against prosecutors bringing charges without any independent screening at all — a modest check by modern standards, but a real one, since a grand jury can and occasionally does return a no bill even when a prosecutor pushes for an indictment. Once charges are filed, the case moves into the broader machinery covered in how the criminal justice system works from arrest to sentencing, and if convicted, into questions of how sentencing guidelines and judicial discretion determine the outcome. The Administrative Office of the U.S. Courts publishes background on federal jury service, including grand jury duty, for citizens called to serve.