A traverse jury, also called a petit jury or trial jury, decides whether a defendant is guilty or innocent during a criminal or civil trial. A grand jury, by contrast, meets in secret to determine whether there is enough evidence to formally charge someone with a crime. The traverse jury renders a verdict after hearing evidence at trial, while the grand jury issues an indictment before trial begins.
What Is a Traverse Jury?
The traverse jury is the group most people picture when they think of jury duty. It sits in the courtroom during trial. Twelve citizens (or sometimes fewer in civil cases) listen to testimony, review evidence, and apply the law as instructed by the judge.
In criminal cases, a traverse jury must unanimously find the defendant guilty beyond a reasonable doubt to convict. In civil matters, the standard is lower: preponderance of the evidence. Some states allow non-unanimous verdicts in civil trials.
The term “traverse” comes from the Latin transversus, meaning “turned across.” Historically, it referred to the jury crossing or traversing the claims made by opposing parties. Modern courts rarely use the term anymore, preferring “trial jury” or “petit jury” to avoid confusion.
What Is a Grand Jury?
A grand jury operates outside the courtroom and in secrecy. It typically includes 16 to 23 citizens who meet periodically over weeks or months. Prosecutors present evidence and witness testimony. No defense attorney is present. No judge presides.
The grand jury’s sole task is to decide whether probable cause exists to indict someone for a felony. It does not determine guilt. The standard is far lower than the beyond-a-reasonable-doubt threshold used at trial.
Federal law and about half of U.S. states require grand jury indictments for serious felonies. The Fifth Amendment to the U.S. Constitution guarantees the right to a grand jury in federal prosecutions. States may use preliminary hearings before a judge instead, depending on their constitutions and statutes.
Key Differences Between Traverse Jury and Grand Jury
| Feature | Traverse Jury (Trial/Petit Jury) | Grand Jury |
|---|---|---|
| Size | 6-12 members (usually 12 in criminal cases) | 16-23 members |
| Function | Decides guilt or innocence at trial | Decides whether to indict (charge) a suspect |
| Stage | After charges are filed, during trial | Before charges are filed |
| Standard of proof | Beyond a reasonable doubt (criminal), preponderance (civil) | Probable cause |
| Public or private | Public, open courtroom | Secret, closed proceedings |
| Defense presence | Defense attorney cross-examines, presents evidence | No defense attorney present |
| Judge present | Yes, presides over trial | No judge in grand jury room |
| Verdict type | Guilty/not guilty (criminal), liable/not liable (civil) | True bill (indictment) or no bill |
| Duration | Days to weeks (one trial) | Weeks to months (many cases) |
How Does a Traverse Jury Work in Practice?
Jurors are summoned from voter rolls, DMV records, or other lists. During voir dire, attorneys question potential jurors to uncover bias. Both sides can strike jurors for cause or use limited peremptory challenges.
Once seated, the jury hears opening statements, witness testimony, cross-examination, and closing arguments. The judge instructs the jury on applicable law. Jurors then deliberate in private until they reach a verdict.
If the jury cannot agree, the judge may declare a mistrial. The prosecution can retry the case with a new jury. In criminal cases, an acquittal is final due to double jeopardy protections.
How Does a Grand Jury Work in Practice?
Grand jurors meet on scheduled days, often once a week. A prosecutor presents one case at a time. Witnesses testify under oath. The prosecutor summarizes the evidence and explains the charges under consideration.
Grand jurors can ask questions directly. They may request additional witnesses or documents. Defense attorneys cannot attend sessions or cross-examine witnesses. In some states, targets of the investigation may testify if they wish, but they risk self-incrimination.
After deliberation, the grand jury votes. If a majority (or supermajority, depending on jurisdiction) finds probable cause, it returns a “true bill” indictment. If not, it issues a “no bill,” and the case cannot proceed unless the prosecutor presents new evidence to a different grand jury or pursues charges another way.
Why Does the U.S. Use Grand Juries?
The grand jury system traces back to 12th-century England. The Founders enshrined it in the Fifth Amendment as a check on prosecutorial power. The idea was that ordinary citizens would shield individuals from unfounded or politically motivated charges.
Critics argue that grand juries are now rubber stamps. Prosecutors control the evidence, and the proceedings are one-sided. The saying “a grand jury would indict a ham sandwich” reflects this skepticism. Defenders counter that grand juries protect privacy, shield innocent people from public accusations, and allow prosecutors to investigate complex crimes thoroughly.
States diverge sharply. Some abolished grand juries decades ago. Others, like New York and Texas, use them extensively. Federal courts always require a grand jury indictment for felonies unless the defendant waives the right.
Can You Serve on Both Types of Jury?
Yes, but not simultaneously. Traverse jury service typically lasts one trial, from a few days to several weeks. Grand jury service runs much longer, often 18 months in federal court or several months in state systems.
A person summoned for traverse jury duty may be called for grand jury service years later, or vice versa. The selection pools and processes differ. Grand jurors are usually chosen from the same public lists, but service is less frequent due to the smaller number of grand juries operating at any time.
State-by-State Variations
Roughly half of U.S. states require or permit grand juries for felony charges [VERIFY exact count as of 2026]. Others use preliminary hearings where a judge decides probable cause in open court. A handful allow prosecutors to file felony charges by information, skipping both the grand jury and preliminary hearing in certain cases.
Trial jury size also varies. Federal criminal trials use 12 jurors. Federal civil trials may seat six. State courts range from six to 12, depending on the case type and severity. Unanimity rules differ: some states accept 10-2 or 9-3 verdicts in civil cases, but the Supreme Court has limited non-unanimous verdicts in criminal trials.
Conclusion
Understanding the difference between a traverse jury and a grand jury is essential for anyone navigating the U.S. criminal justice system. The traverse jury stands as the final arbiter of guilt at trial, while the grand jury serves as a gatekeeper before charges are filed. Both draw on citizen participation, but they operate at opposite ends of the legal process with distinct standards, procedures, and purposes.
Frequently Asked Questions
Is a traverse jury the same as a petit jury?
Yes, traverse jury and petit jury are interchangeable terms for the trial jury that decides guilt or innocence. Courts today more commonly use “trial jury” or “petit jury.” The word traverse is archaic but still appears in some legal texts and statutes.
Can a grand jury find someone guilty?
No. A grand jury only determines whether probable cause exists to charge someone with a crime. It issues an indictment, not a verdict. Guilt or innocence is decided later by a traverse jury at trial, if the case proceeds that far.
Are grand jury proceedings really secret?
Yes. Federal and state rules strictly prohibit disclosing grand jury testimony, transcripts, or votes. Witnesses may discuss their own testimony afterward, but jurors and prosecutors face criminal penalties for unauthorized leaks. The secrecy protects innocent people and ongoing investigations.
Do all states use grand juries?
No. About half of U.S. states require or allow grand juries for felony prosecutions. Others use preliminary hearings before a judge or allow prosecutors to file charges by information. Federal felony prosecutions always require a grand jury indictment unless waived by the defendant.
How long does grand jury service last compared to traverse jury service?
Grand jury service typically lasts several months to 18 months, with jurors meeting periodically to review multiple cases. Traverse jury service lasts only for the duration of a single trial, which may be a few days to several weeks depending on case complexity.
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