The American right to a trial by a jury of one’s peers traces its lineage back to 1297 and the Magna Carta. By the mid-sixteenth century, the jury (known as the petit jury as opposed to the grand jury) had already taken on the form it retains to this day in federal courts and some state courts—twelve citizens were summoned to sit in sworn judgment of the criminal allegations against one of their peers.

The English practice of using juries continued in America from the very first settlements. The Charter of the Virginia Company in 1606 declared that the colonists who were to settle there would enjoy all the rights of Englishmen, which included the right to jury trial. Juries played a vital role in the mid-eighteenth century in resisting English authority in the contest that ultimately led up to the American Revolution. The most noted of the colonial cases was the trial of John Peter Zenger, a New York printer whom the jury acquitted on charges of seditious libel, forty-one years before the drafting of the Declaration of Independence.

King George III responded to such jury nullification of English laws by expanding the jurisdiction of non-jury courts, such as the admiralty courts, and increasingly using those courts as the vehicles for enforcement. Thus it was that in 1776 the Declaration of Independence listed as a grievance against George III his “depriving us . . . of the benefits of trial by jury.” As a consequence, Article III—the portion of the Constitution governing the role of the judiciary—makes clear that judges are not the only judicial actors of constitutional significance. It provides a crucial role for the jury.

There was little debate about this portion of the Constitution, because the need for the criminal jury was one of the few subjects of agreement between Federalists and Anti-Federalists. Alexander Hamilton observed in The Federalist No. 83 that “[t]he friends and adversaries of the plan of the convention, if they agree in nothing else, concur at least in the value they set upon the trial by jury.” The only distinction to be drawn, in his view, was between the Federalist view that it is “a valuable safeguard to liberty” and the Anti-Federalist view that it is “the very palladium of free government.”

Indeed, Thomas Jefferson believed so strongly in the jury that he noted, “[w]ere I called upon to decide whether the people had best be omitted in the Legislative or Judiciary department, I would say it is better to leave them out of the Legislative.” John Adams shared Jefferson’s praise of the jury, observing that “the common people . . . should have as complete a control, as decisive a negative, in every judgment of a court of judicature” as they have in the legislature.

Because judges themselves were part of the government, many Framers feared they would not be an adequate check on government abuse of the criminal process. The jury, therefore, was made part of the original structure of government in order to provide a mechanism for ensuring that individuals would not lose their liberty under a criminal law until the people themselves concurred.

In many criminal cases in the nation’s early history, the jury not only applied the law to the facts it found, but decided questions of law themselves. Thus, many judges refused to tell jurors that they were obliged to accept the judge’s view of the law, and lawyers argued questions of law before the jury in some cases.

Over time, however, this power eroded. In 1895, the Supreme Court concluded in Sparf and Hansen v. United States that the jury did not have the “right” to decide legal questions. As a result, today judges can—and do—instruct juries that they must accept the judge’s view of the law, and lawyers are no longer allowed to argue the merits of the law to the jury. Because the jury possesses authority to issue an unreviewable general verdict of acquittal, the jury nevertheless retains the raw power to check general laws with which it disagrees in individual cases. But because the trial judge does not instruct the jury that it has this authority, the jurors may not know that they have it. In addition, even if the jurors are aware of this power, they must exercise it knowing it is contrary to the judge’s instructions. Hence, there are many cases in which the jury does not exercise that power and instead follows the judge’s instructions, even when the jury itself disagrees with the law in question, with the judge’s interpretation of the law, or with the law’s application in the case before it.

The jury’s power has eroded in a second respect. Prior to 1930, jury trials in federal court, like jurisdictional provisions, could not be waived, reflecting the mandatory language in Article III that the trial of all crimes “shall” be by jury. In Patton v. United States (1930), however, the Supreme Court concluded that a defendant could waive a jury trial in favor of a bench trial. Nonetheless, the prosecutor may still insist upon, and the court must grant, a jury trial.

There are two additional trends in criminal justice that have further diminished the jury’s ability to check the government in criminal cases. First, the vast majority of cases never reach the jury because of the increase in the number of cases resolved by plea bargain.

The second major trend involves the changing nature of sentencing. Congress and many state legislatures have shifted from a model that vested broad sentencing discretion with judges to a regime in which the legislature (or a sentencing commission) specifies in generally applicable laws how particular findings of fact must affect the defendant’s sentence. Thus, these laws are indistinguishable from other criminal laws: they identify blameworthy behavior and specify the criminal punishment for that behavior. But there is a crucial exception: the legislature insists that judges, not juries, apply these laws.

But there are limits to what the legislature can prescribe. In Apprendi v. New Jersey (2000), the Supreme Court held that the legislature does not have unbounded authority to label criminally blameworthy facts as sentencing factors (instead of substantive elements of the criminal offense itself), because such authority could undercut the jury’s constitutional role. The Court in Apprendi therefore held that it is unconstitutional for the legislature to remove from the jury the assessment of facts (other than recidivism) that increase the statutorily prescribed range of penalties to which a defendant is exposed. In Blakely v. Washington (2004), the Court made clear that “the ‘statutory maximum’ for Apprendi purposes is the maximum sentence a judge may impose solely on the basis of the facts reflected in the jury verdict or admitted by the defendant . . . without any additional findings.” This subsequently led the Supreme Court to conclude that the federal sentencing guidelines in their mandatory form ran afoul of the Constitution’s jury guarantee because they required judges, as opposed to jurors, to find facts that “the law makes essential” to a defendant’s punishment by mandating that they must increase a sentence in a particular way. United States v. Booker (2005). As a remedy, the Court made the federal guidelines “advisory” instead of mandatory.

Article III (and the Sixth Amendment) also contain provisions relating to venue, the place where a case is to be tried, and vicinage, the place from which the members of the jury pool trying the case are to be drawn. The Declaration of Independence condemned the English practice of transporting colonial defendants overseas to England for trial by juries of Englishmen. In response, the Constitution guarantees a criminal defendant both the right to be tried in the state where his alleged crime was committed and by a jury drawn from the population of the state and district where the alleged crime occurred.