When Is a Jury Involved in the Criminal Process?

Meta description: Learn when juries participate in U.S. criminal cases, from grand jury indictments and jury selection through trial and verdict—and which stages are handled by judges instead.

In the United States, a jury is involved in only certain parts of a criminal case. A grand jury may consider whether prosecutors have enough evidence to bring serious charges, while a trial jury may decide whether the prosecution has proved guilt. Between those points, jurors are selected, hear evidence, follow a judge’s instructions, and deliberate. Many cases end without a jury trial, and judges generally handle sentencing and appeals. The exact process depends on whether the case is in state or federal court, the charges, and the defendant’s choices.

At a Glance: The Stages That May Involve a Jury

Jury involvement is not continuous from arrest to appeal. It usually occurs at one or both of two stages: a grand jury proceeding in some cases and a jury trial when the case is not resolved earlier. A jury may also be involved in a limited number of post-conviction proceedings, depending on the issue and applicable law.

What a Jury Does in a Criminal Case

A jury is a group of community members selected to make decisions under the law. In a criminal trial, jurors generally decide questions of fact: what happened, whether witnesses are credible, and whether the evidence proves each required element of a charged offense. The judge decides questions of law, manages the courtroom, rules on objections, and explains the legal standards jurors must apply.

Criminal juries are commonly called petit juries to distinguish them from grand juries. A petit jury hears evidence at trial and returns a verdict. A grand jury, where used, considers whether there is sufficient legal basis to formally charge someone. The two bodies have different purposes, procedures, and standards; a grand jury does not determine guilt.

Stage One: Grand Jury Review and Indictment

In some criminal cases, especially serious cases, prosecutors present evidence to a grand jury. The grand jury decides whether there is probable cause to believe the person committed an offense and whether to issue an indictment. An indictment is a formal charging document. It permits a case to proceed, but it is not a finding of guilt.

Federal law generally requires a grand jury indictment for a federal felony, subject to constitutional exceptions and a defendant’s ability to waive indictment. Federal misdemeanors do not always require an indictment. State rules differ: some states use grand juries for certain charges, while others commonly allow prosecutors to proceed through a preliminary hearing or another charging process.

Grand jury proceedings are generally secret. The prosecutor presents evidence and explains the proposed charges. The accused and defense lawyer usually do not participate in the same way they would at a trial, and the grand jury does not ordinarily hear a full adversarial presentation from both sides. The specific rules depend on the jurisdiction.

Because the grand jury’s task is limited, its decision should not be confused with a trial verdict. The prosecution does not have to prove guilt beyond a reasonable doubt at this stage. If jurors return an indictment, the defendant can still challenge the charges, negotiate a plea, or go to trial. If no indictment is returned, prosecutors may have other options under local law.

Stage Two: Pretrial Proceedings Usually Have No Jury

After formal charges, the case typically moves through court appearances and pretrial procedures. These can include an initial appearance, arraignment, bail or release decisions, motions, discovery, and hearings about whether evidence may be used at trial. These proceedings are usually decided by a judge, not a jury.

At arraignment, the defendant is informed of the charges and enters a plea, commonly guilty or not guilty. During discovery, each side exchanges or obtains evidence according to governing rules. The defense may file motions challenging a search, seeking to suppress a statement, or asking the court to dismiss a charge. The judge evaluates the applicable law and record.

Some hearings involve testimony, but that does not make them jury trials. For example, a judge may hear evidence about a disputed search or a request to exclude a confession. The judge decides the legal issue. Witnesses at a pretrial hearing are not ordinarily being questioned by a jury deciding guilt.

Jury Selection: Voir Dire

If the case is going to a jury trial, the court first selects jurors from a pool, often drawn from voter-registration lists, driver’s-license records, or other authorized sources. The selection process is called voir dire. The judge and, depending on the court’s rules, the lawyers ask prospective jurors questions to identify bias, conflicts, or circumstances that could prevent fair consideration of the case.

A prospective juror may be excused for cause if the judge finds a legally sufficient reason, such as an inability to follow the law impartially. Each side may also have a limited number of peremptory challenges, which generally do not require the same showing as a challenge for cause. However, peremptory challenges cannot lawfully be used to exclude jurors because of race or sex. The court seats a jury that meets applicable requirements; many criminal trials also include alternate jurors.

Jury size and the number of votes required for a verdict depend on the type of case and governing law. In federal criminal cases, a jury must generally have 12 members unless the parties agree otherwise under the rules, and a verdict must be unanimous. State law varies, although constitutional rules place limits on nonunanimous verdicts. The judge tells the jury the relevant requirements before deliberations.

Stage Three: The Jury Trial

At trial, the jury’s central responsibility is to decide whether the prosecution has proved the charge beyond a reasonable doubt. This is the highest standard commonly used in U.S. courts. The defendant is presumed innocent, and the prosecution carries the burden of proof. A defendant does not have to prove innocence or testify; the jury generally may not treat a defendant’s decision not to testify as evidence of guilt.

Opening statements and evidence

The prosecution usually presents its case first, followed by the defense if it chooses to present evidence. The lawyers’ opening statements describe what they expect the evidence to show, but statements by attorneys are not themselves evidence. Evidence may include witness testimony, documents, recordings, physical items, or expert opinions, subject to rules governing relevance, reliability, and admissibility.

Jurors assess the admitted evidence and witness credibility. They may take notes if the court permits it, but they must not investigate the case independently, search online, visit a location, or discuss the evidence with others before deliberations. These restrictions help ensure that the verdict is based on evidence presented in court and tested under procedural rules.

Instructions, closing arguments, and deliberations

After the evidence closes, the judge instructs jurors on the law. The instructions explain the elements of each charge, the burden of proof, and how jurors should evaluate the case. The lawyers then make closing arguments, connecting the evidence to their positions. As with opening statements, closing arguments are advocacy, not evidence.

The jury deliberates privately and considers whether the prosecution met its burden on every required element. A jury may find the defendant guilty, not guilty, or—if it cannot reach the required agreement—become deadlocked. A deadlocked jury can lead to a mistrial, after which prosecutors may decide whether to retry the case. The details depend on the court and circumstances.

How a Case Can End Without a Jury Verdict

Many criminal cases do not reach a jury trial. A defendant may plead guilty or, where permitted, no contest; prosecutors may dismiss charges; or the court may resolve a case through another lawful procedure. A plea generally means the defendant gives up the right to have a jury decide guilt, although a judge must follow required safeguards before accepting it.

A defendant may also choose a bench trial, in which a judge—not a jury—hears the evidence and decides guilt. In federal court, a jury-trial waiver generally requires the defendant’s written consent, the government’s consent, and the court’s approval. State procedures vary. The constitutional jury-trial right is important, but it does not mean every criminal case must end with a jury verdict.

Stage Four: Sentencing Usually Belongs to the Judge

When a jury returns a guilty verdict, the case typically proceeds to sentencing. In most cases, the judge imposes the sentence after considering the law, the facts, sentencing rules or guidelines, and information presented by the parties. The jury’s role in deciding guilt is generally separate from the judge’s role in selecting a lawful penalty.

There are significant exceptions. In capital cases, the jury may decide whether a death sentence is legally available or recommend a sentence, depending on state law and applicable constitutional requirements. In some federal cases, a jury may need to find certain facts that increase a legally available maximum penalty, unless the defendant admits those facts. A jury may also have a role in determining criminal forfeiture or other issues under particular statutes and procedures.

For that reason, it is too broad to say that juries never participate after a guilty verdict. The usual rule is that the judge sentences, but the particular charge and jurisdiction matter. Sentencing may also involve a separate hearing, victim-impact statements, presentence information, and arguments from the prosecution and defense.

Stage Five: Appeals and Post-Conviction Review

An appeal is generally decided by appellate judges, not a new jury. The appellate court reviews the trial record and legal arguments to determine whether a significant legal error occurred. It usually does not rehear witnesses or decide the case from scratch. Depending on the issue and result, the court may affirm the judgment, reverse it, or send the case back for further proceedings.

Post-conviction proceedings, such as certain motions or petitions alleging constitutional violations, are also generally decided by judges. Some procedures can involve evidentiary hearings, but a hearing before a judge is not automatically a jury proceeding. Rare statutory or constitutional issues may create exceptions, so local legal advice is important for a specific case.

Federal and State Rules Can Differ

The Constitution provides important protections, including the Sixth Amendment right to a jury trial in qualifying criminal prosecutions. The Supreme Court has applied that right to the states for serious offenses. The right does not extend in the same way to every petty offense, and other constitutional protections may apply based on the potential penalty and circumstances.

State and federal systems differ in charging practices, jury size, selection rules, sentencing procedures, and available post-trial remedies. A state may use a preliminary hearing instead of a grand jury indictment for some cases. Federal procedure has its own rules for indictments, jury waivers, and verdicts. A person facing charges should consult a licensed criminal defense attorney in the relevant jurisdiction rather than assume that a rule from another state applies.

Key Takeaways About Jury Involvement

• Grand jury: May decide whether there is probable cause to issue an indictment; it does not decide guilt.
• Pretrial stage: Judges usually decide bail, motions, and other legal issues without a jury.
• Trial: A petit jury may determine guilt if the case proceeds to a jury trial.
• Alternatives: A plea, dismissal, or bench trial can end a case without a jury verdict.
• Sentencing and appeal: Judges usually handle sentencing and appellate review, although specific exceptions exist.

In short, a jury’s primary role is to evaluate facts at trial, with a possible earlier role in grand jury charging. It does not supervise every step of a criminal case. Whether a jury is involved—and what it is asked to decide—depends on the charge, the defendant’s choices, and the rules of the court handling the case.