A jury is a group of ordinary citizens, sworn in by a court, who listen to evidence in a legal case and decide the outcome. In the United States, juries come in two forms: a grand jury, which decides whether there is enough evidence to formally charge someone with a crime, and a trial jury (sometimes called a petit jury), which decides whether a criminal defendant is guilty or which side wins a civil lawsuit. The right to have your case heard by a jury rather than a single judge is written into the Constitution, and it is one of the few places in American government where decisions of real consequence rest entirely with members of the public.
The Two Types of Juries
Most people picture only one kind of jury: twelve people in a courtroom, listening to lawyers, then filing out to deliberate. That is the trial jury. The other kind, the grand jury, does its work earlier and out of sight.
Grand Juries
A grand jury meets before a criminal case ever goes to trial. Its job is to review the prosecutor’s evidence and decide whether there is probable cause to believe a crime was committed. If the jurors agree, they issue a formal charge called an indictment. If they do not, the case stops there. A grand jury never decides whether someone is guilty.1United States Courts. Types of Juries
Federal grand juries have 16 to 23 members and work in secret. Only the jurors, the prosecutor, any witness being questioned, a court reporter, and any needed interpreter may be in the room, and everyone involved is bound by strict secrecy rules. The privacy protects people who are investigated but never charged, and it encourages witnesses to speak candidly.2Legal Information Institute. Federal Rules of Criminal Procedure Rule 6 – The Grand Jury
Trial (Petit) Juries
Trial juries decide the actual case. The size and rules depend on whether the trial is criminal or civil.
A federal criminal jury has 12 members. The verdict must be unanimous. Every juror has to agree, and if even one holds out, the judge declares a mistrial and the prosecution has to decide whether to start over with a new jury. The Supreme Court confirmed in 2020 that the Sixth Amendment requires unanimity for any serious criminal conviction, in both federal and state court.3Supreme Court of the United States. Ramos v. Louisiana The prosecution has to prove guilt beyond a reasonable doubt, which is the highest standard of proof in American law.1United States Courts. Types of Juries The parties may agree in writing to a smaller jury, and if a juror has to be excused after trial begins, the court may allow the remaining 11 to return a verdict.4Legal Information Institute. Federal Rules of Criminal Procedure Rule 23 – Jury or Nonjury Trial
Federal civil juries can have 6 to 12 members, and all seated jurors take part in the verdict.5Office of the Law Revision Counsel. Federal Rules of Civil Procedure Rule 48 – Number of Jurors; Participation in Verdict The standard of proof is lower. The plaintiff only has to show that their version of events is more likely true than not, called preponderance of the evidence.1United States Courts. Types of Juries Unanimity is the default, but both sides can agree to accept a non-unanimous verdict.
What a Jury Decides, and What a Judge Decides
Inside a trial, the work is split. The jury decides the facts: what happened, who is telling the truth, what the evidence shows. The judge decides the law: what rules apply, what evidence the jury is allowed to hear, and what legal standard the jury has to use. Before deliberations begin, the judge gives the jury a set of instructions spelling out those standards, such as the presumption that a criminal defendant is innocent and that the government carries the full burden of proof. Jurors have to follow those instructions even if they personally disagree with them.
A jury trial is not mandatory. In civil cases, if neither side formally requests a jury, the case is heard by a judge alone.6Legal Information Institute. Federal Rules of Civil Procedure Rule 38 – Right to a Jury Trial; Demand Criminal defendants can also waive a jury, with the court’s approval, and ask for a bench trial instead, where the judge decides both the facts and the law.
Where the Right to a Jury Comes From
Three amendments to the U.S. Constitution set up the jury system. The Fifth Amendment says that anyone facing a serious federal crime first has to be charged by a grand jury, with a narrow exception for military personnel on active duty.7Legal Information Institute. Fifth Amendment The Sixth Amendment guarantees anyone accused of a crime a speedy, public trial before an impartial jury drawn from the state and district where the crime happened.8Congress.gov. U.S. Constitution – Sixth Amendment The Seventh Amendment preserves the right to a jury trial in federal civil suits where the amount at stake is more than twenty dollars, a threshold written in 1791 that courts today read broadly.9Congress.gov. U.S. Constitution – Seventh Amendment
How Jurors Are Chosen
Federal law requires that juries be selected at random from a fair cross section of the community.10Office of the Law Revision Counsel. 28 USC 1861 – Declaration of Policy The pool, called the master jury wheel, is built from voter registration lists, with some districts adding other sources like driver’s license records.11Federal Judicial Center. Handbook on Jury Use in the Federal District Courts People drawn from the wheel are mailed a qualification questionnaire, and those who meet the eligibility rules move into the pool of potential jurors.
When a case needs a jury, a group of those potential jurors is brought into the courtroom for questioning. This stage is called voir dire. The judge and the attorneys ask questions designed to uncover bias or conflicts of interest. A juror who turns out to know one of the parties, has already made up their mind about the case, or cannot be impartial for some other reason can be removed through a challenge for cause, and there is no limit on how many jurors can be removed this way.
Each side also gets a limited number of peremptory challenges, which let them remove a juror without giving any reason.12Office of the Law Revision Counsel. Federal Rules of Criminal Procedure Rule 24 – Trial Jurors One rule limits them: in Batson v. Kentucky, the Supreme Court held that the Equal Protection Clause forbids striking jurors because of their race, and even a single racially motivated strike is unconstitutional.13Justia Law. Batson v. Kentucky, 476 U.S. 79 (1986)
Who Can Serve
Federal law sets four basic requirements for jury service, all of which have to be met:14Office of the Law Revision Counsel. 28 U.S. Code 1865 – Qualifications for Jury Service
- You are a U.S. citizen, at least 18 years old, and have lived in the judicial district for at least a year.
- You can read, write, speak, and understand English well enough to follow the proceedings and complete the qualification form.
- You have no physical or mental condition that would prevent you from serving.
- You are not currently charged with a crime punishable by more than a year in prison, and have not been convicted of one unless your civil rights have been restored.
State courts have their own qualification rules, which generally track these categories but can differ in the details.
What Happens If You’re Summoned
Federal jurors are paid $50 for each day they attend court, plus a travel allowance and, if an overnight stay is needed, a subsistence allowance for meals and lodging.15Office of the Law Revision Counsel. 28 USC 1871 – Fees State rates vary widely and are often much lower.
Your job is protected. Federal law prohibits employers from firing, threatening, or punishing any permanent employee for serving on a jury. An employer who does so faces a civil penalty of up to $5,000 per violation and can be ordered to reinstate the employee with full seniority, as though they had been on a leave of absence. The court can also appoint an attorney for the employee at no cost if the claim has merit.16Office of the Law Revision Counsel. 28 U.S. Code 1875 – Protection of Jurors’ Employment
Ignoring a summons has real consequences. Anyone who fails to appear can be ordered to show up and explain why. Without a good reason, the penalty is a fine of up to $1,000, up to three days in jail, mandatory community service, or some combination of those.17Office of the Law Revision Counsel. 28 USC 1866 – Selection and Summoning of Jury Panels Courts routinely grant postponements for legitimate scheduling conflicts. Throwing the summons away is the one response that never works.