A jury is a sworn body of people (the jurors) convened to render an impartial verdict (a finding of fact on a question) officially submitted to them by a court, or to set a penalty or judgment. Juries developed in England during the Middle Ages, and are a hallmark of the Anglo-American common law legal system. They are still commonly used today in Great Britain, the United States, Canada, Australia, and other countries whose legal systems are descended from England's legal traditions. Most trial juries are "petit juries", and usually consist of twelve people. A larger jury known as a grand jury was used to investigate potential crimes and render indictments against suspects, but all common law countries except the United States and Liberia have phased these out. The modern criminal court jury arrangement has evolved out of the medieval juries in England. Members were supposed to inform themselves of crimes and then of the details of the crimes. Their function was therefore closer to that of a grand jury than that of a jury in a trial.