Did you ever serve on a jury? You took your seat in a panel of twelve jurors solemnly sequestered behind a soundproof door. Then came a shock. Seven jurors reached the verdict. The others went with the majority. That was my experience. So why empanel twelve people to do the work of seven?
Blame King Henry II of England. Henry won the throne of England in 1154 after nineteen years of civil war left the country in ruins. He spent his first decade as king restoring what years of strife had destroyed, including the judicial system. A man of tireless energy, Henry worked with his chancellor, Thomas Becket, to create a code of laws and penalties to be interpreted in new county courts by incorruptible officers. Judicial systems in many English-speaking countries descend from the model that Henry wrote into law at Clarendon in 1166.
But why empanel exactly “twelve just men” to “report malefactors”? Henry’s queen, Eleanor of Aquitaine, explains: “Henry showed populist leanings in curious ways. He set his legalists striving to codify the common law, and twelve is the common measure in the market-place.”
Indeed, twelve was the common market measure. Not ten. Counting ten fingers takes you to ten, and you can’t measure quarters and thirds in whole numbers. But twelve, a dozen (douzaine), takes you to a gross, 144, while whole numbers (multiples of three and four) express quarters and thirds.
Try it! Use your left thumb to tally the number of bones in the other four fingers of that hand. You’ll count twelve. Now transfer your left hand’s score, twelve, into “Memory” by using your right thumb to tally twelve on the first bone of your right forefinger. The left hand keeps the active tally (e.g. measures of peas, apples, sausages, onions, turnips or livestock) while the right hand keeps track of the twelves to subtotal the “bottom line.” Twelve was the benchmark for commerce.
And the benchmark for juries? What suited trade suited King Henry’s justice.
Henry achieved his reforms at a time of vicious discord with Thomas Becket, and with Eleanor, Henry’s queen. Eleanor removed herself from Henry’s court in England to protest his flouting his mistress, “Fair” Rosamond Clifford.
We can imagine Eleanor saying, “Let Henry draft his Constitutions, his Assize! Let him prefer his twelve just men! Let him judge England!”
Fired by her own passion for reform, Eleanor set up her Court of Ladies in her capital city, Poitiers, where women debated “courtly love” and addressed their rights, devising Eleanor’s Code of Poitiers. “I imagined for women a state above strife and far above men. Would that our human estates were ruled by twelve just women!”
The supremacy of base-twelve in trade dates from before the reign of Charlemagne, who died in 814. Charlemagne never ruled England, but good ideas travel. Henry II adopted base-twelve for English money as well as commerce. For nearly eight hundred years a shilling was worth twelve pence.
So! Measures of peas, grain, sausages, livestock, pennies and jurors. All over the planet, jurors still file in and out of courts, in twelves.