The Supreme Court is set to decide in the next few weeks whether to hear Parada v. United States, a case that asks the court to reinstate 12-person juries.

For much of American history, the right to a jury meant a right to 12 jurors. The 12-juror requirement was inherited from centuries of English common law, carried to America, and adopted by the 13 original colonies. But in 1970, the Supreme Court did away with the requirement, reasoning that trial courts should have leeway to call in fewer members of the community for jury service. The justices, writing in 1970, noted that they did not find anything in the records of the Constitutional Convention to suggest that the founders cared, one way or another, about the number of jurors impaneled for trial.

In the intervening decades, constitutional historians have uncovered a wealth of archival documents revealing what 18th century Americans really thought about the question. The founders cared, to put it mildly. When the Constitution was ratified, if you wanted to signal someone was receiving second-class justice—that constitutional protections didn’t apply—you gave them fewer than 12 jurors. Fewer jurors meant you weren’t worthy of the dignity of a constitutional trial.

Nowhere is that understanding clearer than in the so-called “slave courts” of the Carolinas. These courts originated in the 1690 Act for the Better Ordering of Slaves and operated for more than 150 years outside constitutional protection, explicitly denying enslaved people the trial rights that white Americans enjoyed. And here’s what’s revealing: enslaved people facing trial in these courts received as few as three and as many as five jurors—but crucially, never 12.

Courts of the era were explicit about what that meant. A trial with fewer than 12 jurors was, in the words of South Carolina Chief Justice John Belton O’Neall, “not a trial by jury, in any sense in which the words have ever been legally used.”

Slave courts tried criminal cases against both enslaved and free Black Americans. Surviving records indicate that the most frequently tried cases involved charges of petty larceny or disorderly conduct, with an average sentence of “fifty lashes at the whipping post”—sometimes administered in weekly installments when the pain proved unbearable in a single session. But these courts also wielded the power to impose the death penalty. When they did, taxpayer money compensated slaveowners for what amounted to government destruction of their property. Perversely, many slaveowners actually initiated capital cases against the people they enslaved, preferring execution and taxpayer compensation to the continued ownership of anyone they deemed “recalcitrant.”

This issue came to a head in an 1844 case involving the owner of an enslaved woman named Emma. The owner contested a verdict by the slave court requiring him to forfeit any enslaved person he took north of the Potomac River. The South Carolina law sought to dissuade slaveholders from taking enslaved people into free states, fearing they might return “contaminated” by abolitionist ideas. He argued that, although Emma herself had no right to a jury—and therefore could be tried criminally before five jurors—his “property rights” could not be forfeited without a verdict by 12 jurors.

The South Carolina appellate court agreed, writing that a trial by five jurors is “not a trial by jury” and is “utterly inconsistent with a due course of law.”

According to the founders, even enemies of the Revolution deserved 12 jurors. Consider New Jersey in 1780, the middle of the Revolutionary War. The state sat between American and British forces, and smugglers accused of aiding the British posed a genuine threat to the independence cause. The legislature had unanimously passed a law allowing six-person juries to try accused traitors. Yet the state’s supreme court struck it down as unconstitutional under New Jersey’s own 1776 constitution, an early precursor to the federal Bill of Rights. Chief Justice David Brearley, who would later serve as a delegate to the Constitutional Convention, explained that even alleged smugglers aiding the British in the nation’s darkest hour, with independence hanging in the balance, deserved the dignity of 12 jurors.

When Americans gathered to debate the Constitution at their state ratifying conventions, the 12-juror requirement was a given. In Virginia, Governor Edmund Randolph, who had served as a delegate at the Constitutional Convention just months before, now presided over his state’s ratification debate. When critics questioned the Constitution’s jury provision, Randolph defended the document by noting there was “no suspicion that less than 12 jurors will be thought sufficient.” The requirement, he suggested, was implicit in the word “jury.”

Widely-read literature of the time also reveals how the founders thought about the right to a jury. One dictionary available at the founding, Giles Jacob’s A New Law Dictionary, enjoyed unparalleled popularity—catalogued in the private libraries of John Adams and Thomas Jefferson, among many others.

Jacob’s dictionary defines “verdict” as requiring “every one of the 12 jurors” to agree, noting that “if there be 11 jurors agreed and but one dissenting the verdict shall not be taken.” Likewise, “tales”—replacement jurors called when someone couldn’t serve—were said to be needed to reach “the number of 12.” The number wasn’t incidental, in other words. It was definitional.

William Blackstone’s Commentaries, a multi-volume treatise and the preeminent authority on common law for the founding generation, stated that no person could be affected “in his property, his liberty, or his person, but by the unanimous consent of twelve of his neighbours and equals.” And another leading 18th-century lawbook, one by Sir Matthew Hale, addressed what would happen if one juror left during deliberations, leaving only 11. His answer was unequivocal: “no verdict can be taken of the 11, and if it be, it is error.” The remaining 11 must “be discharged, and a new jury sworn.” The founders apparently knew what they were codifying in the Bill of Rights—not an approximation, not a range, but 12.

A 12-person jury means 12 perspectives, 12 life experiences, 12 chances for a lone voice to speak up and say, “Wait, something’s not right here.” Cut that number, and the verdict becomes less representative of the community. Americans scarred by political prosecutions under British rule sought to ensure that verdicts reflected the community’s judgment, not a prosecutor’s agenda or a judge’s loyalties. A 12-person jury serves as democracy’s circuit breaker; it aims to force consensus, temper bias, and demand persuasion across differences.

In 1970, the Supreme Court concluded that history was silent on the question of jury size. But the slave courts of the Carolinas were never silent. The New Jersey Supreme Court at the height of the Revolutionary War was never silent. The dictionaries on the founders’ bookshelves were never silent. The question is whether, 55 years later, we’re finally ready to listen.

Wanling Su is an Assistant Professor at Indiana University Bloomington, whose scholarship examines the historical foundations of the constitutional jury right. She recently published an article in North Carolina Law Review, together with Georgetown Research Fellow Rahul Goravara, titled “What is a Jury?” documenting how the founding generation understood jury composition. She has also filed an amicus brief in Parada v. United States (No. 25-166) asking the Supreme Court to require 12-person juries again.

Made by History takes readers beyond the headlines with articles written and edited by professional historians. Learn more about Made by History at TIME here. Opinions expressed do not necessarily reflect the views of TIME editors.