A jury is a group of people who are sworn to give a verdict on a matter submitted to them by a court or to set a penalty or judgment. Juries are most common in common law adversarial-system jurisdictions. There are two types of juries serving different functions in the federal trial courts: petit juries and grand juries.

• Petit Jury: Petit juries, also known as trial juries, decide both criminal and civil cases. In a criminal case, a petit jury decides whether the Government has proved beyond a reasonable doubt that the defendant committed the crime as charged. In a civil case, a petit jury decides whether the plaintiff establishes with evidence that is more likely than not, known in legal terms as preponderance of the evidence, that the defendant injured the plaintiff in some way that requires appropriate compensation. Petit juries are comprised of 6-12 people, and trials are generally public, but jury deliberations are private. Petit juries render a verdict, of guilty/not guilty in a criminal case, or in favor of a defendant or plaintiff in a civil case. Petit jurors hear a maximum of one case and are then discharged.

• Grand Jury: A grand jury focuses on preliminary criminal matters only and assesses evidence presented by a prosecutor to determine whether there is “probable cause” to believe an individual committed a crime and should be put on trial. If the grand jury determines there is enough evidence, an indictment is issued. Grand juries are comprised of 16-23 people, and their proceedings are secret. Grand jurors serve for a longer period of time than petit jurors.

Serving on a jury is normally compulsory for individuals who are qualified for jury service. A jury is intended to be an impartial panel capable of reaching a verdict. Procedures and requirements may include a fluent understanding of the language and the opportunity to test jurors neutrality or otherwise exclude jurors who are perceived as likely to be less than impartial.