Jury - Trial Jury Size

Trial Jury Size

The size of the jury is to provide a "cross-section" of the public. In Williams v. Florida, 399 U.S. 78 (1970), the Supreme Court of the United States ruled that a Florida state jury of six was sufficient, and that "the 12-man panel is not a necessary ingredient of "trial by jury," and that respondent's refusal to impanel more than the six members provided for by Florida law did not violate petitioner's Sixth Amendment rights as applied to the States through the Fourteenth."

In Brownlee v The Queen (2001) 207 CLR 278, the High Court of Australia unanimously held that a jury of 12 members was not an essential feature of "trial by jury" in section 80 of the Australian Constitution.

In Scotland, a jury in a criminal trial consists of 15 jurors, which is thought to be the largest in the world. In 2009 a review by the Scottish Government regarding the possibility of reduction, led to the decision to retain 15 jurors, with the Secretary for Justice stating that after extensive consultation, he had decided that Scotland had got it "uniquely right".

For juries to fulfill their role to analyze the facts of the case, there are strict rules about their use of information during the trial. Juries are often instructed to avoid learning about the case from any source other than the trial (such as from media accounts) and to not attempt to conduct their own investigations (such as independently visiting a crime scene). Parties, lawyers, and witnesses are not allowed to speak with a member of the jury. Doing these things may constitute reversible error. In very rare, high-profile cases, juries may be sequestered for the deliberation phase or for the entire trial.

Conversely, jurors are generally required to keep their deliberations in strict confidence during the trial and deliberations, and in some jurisdictions even after a verdict is rendered. In English law, the jury's deliberations must never be disclosed outside the jury, even years after the case; to repeat parts of the trial or verdict, is considered to be contempt of court, a criminal offense. In the United States, this rule usually does not apply, and sometimes jurors have made remarks that called into question whether a verdict was properly arrived at. In Australia, academics are permitted to scrutinize the jury process only after obtaining a certificate or approval from the Attorney-General.

Because of the desire to prevent undue influence on a jury, jury tampering (like witness tampering) is a serious crime, whether attempted through bribery, threat of violence, or other means. Jurors themselves can also be held liable if they deliberately compromise their impartiality.

A study by the University of Glasgow showed that a jury of 12 people was ineffective because a few jurors ended up dominating the discussion, and that seven was a better number because more people feel comfortable speaking, and they have an easier time reaching a unanimous decision.