In 1166, the Assize of Clarendon mandated that juries investigate crimes throughout England. Before this decree, ancient Germanic tribes used groups of men to judge accused individuals based on their social standing. The system evolved into the vehmic court in medieval Germany and persisted in parts of Anglo-Saxon England after the Norman Conquest. Henry II's reign saw ordinary community members testifying under oath about local crimes. These early jurors were self-informing, meaning they relied on personal knowledge or hearsay rather than evidence presented in court. By 1215, the Catholic Church banned trial by ordeal, forcing judges to ask jurors if they believed an accused was guilty. King Aethelred the Unready issued a Wantage Code around 997 requiring twelve leading thegns to swear oaths against accusing innocent men. In ancient Athens, jury courts dating back to 500 BCE allowed citizens to annul unconstitutional laws through secret ballots. The modern jury trial emerged from these customs during the mid-12th century when royal justices began supervising trials while sheriffs prepared cases.
Types And Functions
A petit jury typically consists of up to fifteen people who hear evidence in a trial. Grand juries contain between sixteen and twenty-three jurors and determine whether enough evidence exists for a criminal trial to proceed. In the United States federal courts, grand juries issue indictments or presentments regarding alleged crimes. California and Florida utilize grand juries to perform investigative audits similar to government accountability offices. Coroner's juries convene in common law jurisdictions to investigate deaths occurring under ambiguous circumstances. An advisory jury provides non-binding opinions on factual issues to inform a judge who remains the final arbiter. Policy juries serve as randomly selected bodies with purposes other than legal verdicts. The size of a jury varies significantly across different regions. Scotland employs fifteen jurors in criminal trials, which is thought to be the largest group globally. A study by the University of Glasgow suggested that seven members might be more effective for civil juries than twelve.