Quid Pro What?: The Unique and Consequential Language of Law

Sam Quillen
4 min readOct 11, 2022


There was a time when eccentric Western political scandals were the biggest problem on Mr. Zelensky’s plate.

The first impeachment trial US President Donald Trump hinged largely on whether he held out military aid to Ukraine as a bargaining chip to get his counterpart Volodymyr Zelensky to investigate the son of his rival Joe Biden. In other words, was he offering a quid pro quo? For weeks in early 2020, the most important question in the world was the proper interpretation of one phrase in a dead language that has been fossilised in law for thousands of years.

Several phrases in Latin, French, or archaic English are still used today, generally gratuitously by people keen to show off their erudition. But in law, they have serious weight. Every day, judges decide defendants’ fates based on whether they did something with “malice aforethought” or mens rea.

These terms have staying power because there is no precise agreement on what they mean. One could translate mens rea as “guilty mind,” but to put it in such punchy modern English would risk throwing centuries of finely-tuned jurisprudence off kilter. It is the same principle that underlies Muslims’ belief that the Quran can only be properly understood in Arabic. Any translation entails distortion, and some matters are far too important to risk that.

In the 6th Century, Emperor Justinian compiled the Corpus Juris Civilis, a definitive collection of Roman law. He insisted that it be in the original Latin, even though almost all of his subjects spoke Greek. The Code of Justinian (as it was popularly known) was the final word on law across much of Europe until Napoleon published his own in 1804.

Ubiquitous Latin is a well-known (and oft-lamented) fixture of legal language. Not many realise that Latin’s presence is vastly outweighed by another foreign language. When William the Conqueror and his Norman knights conquered England in 1066, they set in motion a total transformation of the English language. Norman French became the official language of the kingdom. Naturally, the realm where England’s new rulers asserted themselves most aggressively was the law.

For centuries, England was the only country in the world where French was the language of law (until 1539, the French still used Latin). The Pleading in English Act 1362 finally allowed Englishmen to speak English in court, but Law French remained a pillar of legal education through the 17th Century. By that time, however, uninterested law students had butchered it so badly that it had become a risible farce.

By 1688, legal French had become so ridiculous that English lawyers decided to stop trying. But it left a massive mark on English: for reference, all the italicised words on the right are originally French.

Today, lawyers do not think of French as an important part of their jargon the way Latin is. That is because French is so integrated into our law that practically all of our legal language is French. Court, trial, crime, contract, judge, justice, attorney, prison, punishment, sentence, and decision are all words that we adopted from the Normans.

In law as in the language as a whole, the integration of French vocabulary with Anglo-Saxon quasi-synonyms makes English a uniquely rich and expressive language. “Breaking and entering” is a doublet combining the Anglo-Saxon “break” with the French “enter,” drawing a meaningful distinction that does not exist in other languages. Breaking and entering is a fairly serious crime. But if you have a good lawyer or attorney, you could get away with it free and clear. Likewise, you could get a disputed sale or transfer declared null and void. It is all part of law and order in our unique language.

Many French words have taken on a life of their own in English. “Mortgage” means “dead pledge” in French; in modern France, one buys a house on a hypothèque. “Tort” comes from the Old French meaning “twist” (it shares that root with “torture,” which both law students and civil action defendants would agree is appropriate). Norman kings employed escheators to seize property that was left behind by men who died without wills, or was otherwise forfeit to the Crown. These rapacious agents got such a bad reputation that their title gave rise to the modern English “cheat.”

Medieval legal experts try their case

In medieval England, the noblest way to determine who was right in a legal case was trial by combat. As society became more enlightened, however, people started to question whether it served justice to decide cases based on who could assault and batter and murder his opponent more effectively. It became fashionable for progressive litigants to hire men with legal training as their squires, then spend literal hours sharpening their swords, tying their shoes, trading gloves, and even going to church together as their squires negotiated a settlement. Trial by combat eventually died out entirely. But it should not surprise anyone that members of a profession who decide 21st Century cases using linguistic concepts from medieval France and ancient Rome still like to style themselves “esquire.”

Note: this topic is one near and dear to my heart these days, as I recently started law school. As the luminary legal scholar Elle Woods observed, Harvard Law is hard, so I have had a bit less time for linguistics blogging than I would like. Things should settle down a bit, and on the bright side, all this bizarre archaic language is better linguistics inspiration than the finance jargon at my old job.

The Bodleian Library at Oxford has served students since the days when all the books were in Latin. If you look closely, the signs still are.



Sam Quillen

Former linguistics student; current investment bank analyst who sometimes thinks about something other than spreadsheets