Jury Duty Explained: Why Citizens Serve and How Trials Actually Work
Receiving a jury summons is one of the few times government directly calls on citizens to participate in the justice system. Understanding how juries are formed, what they decide, and why the system is built around them makes the experience — and the institution — far less mysterious.
Published June 28, 2026Trial by jury is guaranteed by the Sixth Amendment for criminal cases and by the Seventh Amendment for many civil cases. The right is ancient in origin, tracing back to English common law, and it rests on a foundational principle: that judgments about guilt or civil liability should be made by ordinary citizens rather than by government officials alone. Jury service is how that principle becomes practice.
Two types of juries
Most people are familiar with the trial jury, also called a petit jury. This is the group of jurors — typically 12 in criminal cases, though some civil cases use fewer — that hears evidence and returns a verdict. The trial jury decides questions of fact: what happened, whether the defendant did it, and (in criminal cases) whether the government has proved guilt beyond a reasonable doubt.
The grand jury serves a different function. It operates before trial to determine whether there is probable cause to bring criminal charges. Grand juries in federal cases and many state cases hear evidence presented by prosecutors, without the defendant or defense attorneys present, and decide whether an indictment is warranted. Grand jury proceedings are secret, and the standard for returning an indictment is much lower than the standard for a criminal conviction. Critics note that grand juries almost always indict when prosecutors ask them to; defenders argue that the institution provides at least a check on wholly unsupported charges.
How jurors are selected
The process begins with a jury pool. Courts compile lists of potential jurors, typically from voter rolls, driver’s license records, or both. People on those lists receive summonses requiring them to appear at the courthouse on a specified date. Failure to respond to a summons can result in a fine or other penalties, though enforcement varies.
From the pool, a smaller group is called into a courtroom for voir dire — a French phrase meaning roughly “to tell the truth.” In voir dire, the judge and attorneys question potential jurors to identify those who cannot be fair and impartial in a particular case. The questioning aims to surface relationships with the parties, exposure to pretrial publicity, strong opinions on the subject matter, or other factors that might compromise a juror’s ability to decide the case on the evidence.
Attorneys can challenge jurors in two ways. A challenge for cause argues that a specific juror cannot be impartial; these are unlimited but require the judge to agree. A peremptory challenge allows an attorney to dismiss a juror without giving a reason, but each side gets only a limited number. Peremptory challenges cannot lawfully be used to exclude jurors based on race or sex — a limitation established in Batson v. Kentucky (1986) — though proving discriminatory use of a peremptory challenge in practice is difficult.
What jurors decide
A trial jury decides questions of fact, not questions of law. The judge instructs the jury on the relevant legal standards — what elements the prosecution must prove, what “beyond a reasonable doubt” means, how to evaluate witness credibility — and the jury applies those standards to the evidence it has heard. The jury does not decide whether a law is constitutional or whether the defendant should have been charged; it decides whether the facts satisfy the legal standard as the judge has explained it.
In criminal cases, the verdict must generally be unanimous. If jurors cannot agree, the result is a hung jury, which typically leads to a mistrial and may result in a new trial. In civil cases, many jurisdictions allow non-unanimous verdicts. Jurors are prohibited from discussing the case with anyone outside the jury during trial and must reach their verdict based solely on the evidence presented in court.
Exemptions and hardship
Courts recognize that jury service imposes real burdens. Employers are generally required by federal law to allow employees time off for jury service, though pay during that time varies. Many states offer modest per diem payments to jurors, though the amounts are typically far below ordinary wages.
People can be excused from jury service for hardship — situations where serving would cause genuine, substantial difficulty — or for disqualification. Common disqualifications include not being a U.S. citizen, having a felony conviction in many states, and not being a resident of the jurisdiction. Certain professions may qualify for deferral or exemption depending on state law.
Why it matters
The jury system places a check on government power directly in the hands of ordinary citizens. A prosecutor can bring charges; a judge can preside; but a conviction requires twelve peers of the accused to agree. That requirement reflects a deliberate choice to interpose community judgment between state authority and individual liberty.
The system has real limitations. Research on jury decision-making shows that irrelevant factors can influence verdicts. Juries may be swayed by presentation style, appearance, or unconscious bias. These are genuine concerns that have prompted various reforms — jury instructions written in plainer language, measures to reduce implicit bias, and in some proposals, greater use of professional judges in complex cases. But the underlying principle that citizens should participate directly in the administration of justice has proven durable across centuries of legal development.