Mozley and Whitley write of a jury as follows:
"Jury signifies a body of men sworn to inquire of a matter of fact and to declare the truth upon such evidence as shall be delivered them."
In State of New Jersey v James, Justice Walker of the Court of Errors and Appeals of New Jersey wrote that a jury is a:
"... body of twelve men who are sworn to try the facts of a case as they are presented in the evidence."
There is no longer any exclusion of women from serving on juries1 and the typical qualification is no longer ownership of land but simply any person having the right to vote.
In People of the State of Colorado ex rel Hunter, Justice Lee of the Supreme Court of Colorado adopted these words in his opinion:
"[T]he term jury connotes a deliberative body of persons.
"The word jury has been defined as a body of men sworn to give a verdict upon some matter submitted to them; a body of men selected according to law, impaneled and sworn to inquire into and try any matter of fact, and to give their verdict according to the evidence legally produced."
Jury trials are not the exclusive purview of criminal law. In many jurisdictions, juries may also be elected to resolve personal injury litigation.
In the context of criminal law, R v Pan, Madame Justice Arbour, then of Canada's Supreme Court, looked at the meaning of the word jury and wrote, at ¶43-44:
"The jury is a judicial organ of the criminal process. It accomplishes a large part of the function exercised by judges in non-jury criminal cases. In a jury trial, the jury is the judge of the facts, while the presiding judge is the judge of the law. They, judge and jury together, produce the judgment of the court. The jury hears all the evidence admitted at trial, receives instructions from the trial judge as to the relevant legal principles, and then retires to deliberate. It applies the law to the facts in order to arrive at a verdict. In acting as fact-finders in a criminal trial, jurors, like judges, bring into the jury room the totality of their knowledge and personal experiences, and their deliberations benefit from the combined experiences and perspectives of all of the jurors. One juror may remember a detail of the evidence that another forgot, or may be able to answer a question that perplexes another juror. Through the group decision-making process, the evidence and its significance can be comprehensively discussed in the effort to reach a unanimous verdict....
"[T]he jury, unlike a judge, does not provide reasons for its ultimate decision...."
In R. v. G., that same court, Justice Cory writing for the majority waxed eloquent on the origin and importance of the jury in the common law (¶13-15):
"The jury system is clearly a significant factor in many democratic regimes.... It is extremely important to our democratic society that jurors as representatives of their community may make the decision as to the guilt or innocence of the accused before the court based solely on the evidence presented to them. There is a centuries-old tradition of juries reaching fair and courageous verdicts. That tradition has taken root and been so well and fearlessly maintained that it has flourished in this country. Our courts have very properly stressed the importance of jury verdicts and the deference that must be shown to those decisions. Today, as in the past, great reliance has been placed upon those decisions. That I think flows from the public awareness that 12 members of the community have worked together to reach a unanimous verdict.
"In reaching a verdict, jurors have heeded the wisdom of the prophet Isaiah whose advocacy of a reasoned approach to solving problems has echoed through the ages in the moving and memorable words Come now, and let us reason together [Isaiah 1:18]. Of course, it is the great strength and virtue of the jury system that members of the community have indeed come together and reasoned together in order to reach their unanimous verdict. It is truly a magnificent system for reaching difficult decisions in criminal cases. It has proven itself in the centuries past and continues to do so today. Yet, this system is fragile.
"If the process is subjected to unwarranted pressures, or to unnecessary distractions, the delicate reasoning process may be thwarted. The sole task of a jury is to reach a verdict based exclusively on the evidence presented. The sturdy independence of jurors may be overcome and unanimity compelled by a judge’s suggestion that irrelevant factors be considered or by the judge’s exerting unwarranted pressure. In those circumstances, the verdict may no longer be based on a reasoned approach to the evidence. It follows that the instructions given to an apparently deadlocked jury must be delicately balanced and carefully crafted. If they are not, the jury system as a bulwark of democracy will all too easily be breached. The importance and significance of the instructions or exhortation to an apparently deadlocked jury cannot be overemphasized. The jurors at this stage are tired, probably frustrated and certainly disgruntled. They have given so much of their time and laboured so hard with the difficult issues that they are entitled to a careful and balanced instruction. "
In Williams v Florida, Justice White of the United States Supreme Court wrote:
"Providing an accused with the right to be tried by a jury of his peers gave him an inestimable safeguard against the corrupt or overzealous prosecutor and against the compliant, biased, or eccentric judge. Given this purpose, the essential feature of a jury obviously lies in the interposition between the accused and his accuser of the commonsense judgment of a group of laymen, and in the community participation and shared responsibility that results from that group's determination of guilt or innocence."
A distinction once made but now in disuse, but still germane to the United States, is between a petty jury (a jury to hear a regular criminal or criminal case) or a grand jury (a jury seized with the issue as to whether or not sufficient facts exist to merit a criminal accusation).
Note also these wise words of Justice Devlin (1905-1992):
"What makes juries worthwhile is that they see things differently from judges. Trial by jury is the lamp that shows that freedom lives."
The Scottish jurist Brougham wrote of the jury box, in Present State of the Law:
"In my mind, he was guilty of no error, he was chargeable with no exaggeration, he was betrayed by his fancy into no metaphor, who once said that all we about us, Kings, lords and Commons, the whole machinery of the State, all the apparatus of the system, and its varied workings, end in simply bringing twelve good men into a box."