<P> A grand jury decides whether or not there is enough evidence ("probable cause") that a person has committed a crime in order to put him or her on trial . If a grand jury decides there is enough evidence, the person is indicted . A grand jury has 16 - 23 members, and its proceedings are not open to the public . Unlike a petit jury, defendants and their attorneys do not have the right to appear before the grand jury . </P> <P> A petit jury, also known as a trial jury, is the standard type of jury used in criminal cases in the United States . Petit juries are responsible for deciding whether or not a defendant is guilty of violating the law in a specific case . They consist of 6 - 12 people and their deliberations are private . Their decision is known as a verdict and decides whether a person is guilty or not guilty . </P> <P> Currently in the United States every person accused of a crime punishable by incarceration for more than six months has a constitutional right to a trial by jury, which arises in federal court from the Sixth Amendment, the Seventh Amendment, and Article Three of the United States Constitution, which states in part, "The Trial of all Crimes...shall be by Jury; and such Trial shall be held in the State where the said Crimes shall have been committed". Most states' constitutions also grant the right of trial by jury in lesser criminal matters, though most have eliminated that right in offenses punishable by fine only . The Supreme Court has ruled that if imprisonment is for six months or less, trial by jury is not required, meaning a state may choose whether or not to permit trial by jury in such cases . </P> <P> Specifically, the Supreme Court has held that no offense can be deemed' petty' for purposes of the right to trial by jury where imprisonment for more than six months is authorized . Justice Black and Justice Douglas concurred, stating that they would have required a jury trial in all criminal proceedings in which the sanction imposed bears the indicia of criminal punishment . Chief Justice Burger, Justice Harlan and Justice Stewart objected to setting this limitation at six months for the States, preferring to give them greater leeway . No jury trial was required when the trial judge suspended sentence and placed defendant on probation for three years . There is a presumption that offenses carrying a maximum imprisonment of six months or less are petty, although it is possible that such long an offense could be pushed into the serious category if the legislature tacks on onerous penalties not involving incarceration . No jury trial is required, however, when the maximum sentence is six months in jail, a fine not to exceed $1,000, a 90 - day driver's license suspension, and attendance at an alcohol abuse education course . The Supreme Court found that the disadvantages of such a sentence, "onerous though they may be, may be outweighed by the benefits that result from speedy and inexpensive nonjury adjudications ." Such interpretations have been criticized on the grounds that "all" is not a word that constitution - makers use lightly . </P>

The u.s. supreme court has held that in all criminal cases the defendant has a right to a jury trial