A corrupt French dialect used by English lawyers from after the Norman Conquest in 1066 until slightly after the end of the Restoration period in 1688.
By the mid–thirteenth century, many of the English gentry and some commoners spoke French, and the language was used in the king's courts and in printed legal materials. After England's wars with France during the reign of Edward III (1327–77), schools no longer taught French. Oral French in the courts was thereafter mostly confined to recitation of formal pleadings, and thus lost grammatical sophistication and suffered a drastic decline in vocabulary.
Law French was primarily a written language and was pronounced as if it were English. It persisted because of tradition and because most of the books in lawyers' libraries were printed in French or in Latin. It also functioned as a form of shorthand for lawyers to use in recording legal propositions. In other words, spoken English was transcribed in French. This use resulted in an artificial technical vocabulary, uncorrupted by the vicissitudes of vernacular English usage. The names of everyday things became increasingly Anglicized, but law French terminology formed the cornerstone of the common-law vocabulary. Some of the words still used today are appeal, arrest, assault, attainder, counsel, covenant, debtor, demand, disclaimer, escrow, heir, indictment, joinder, lessee, larceny, merger, negligence, nuisance, ouster, proof, remainder, tender, suit, tort, trespass, and verdict.
By the mid-Tudor period, in the mid-sixteenth century, the active law French vocabulary consisted of fewer than a thousand words; English was freely substituted for French when the writer's knowledge of French proved inadequate. In 1650 Parliament enacted a statute prohibiting the use of law French in printed books. At the beginning of the Restoration, in 1660, the law was treated as void and there was a widespread, albeit short-lived, reversion to law French. Law French gradually died in the ensuing years. It appears that the last english law book written in law French was published in 1731. Sir John Comyn, Chief Baron of the Court of Exchequer, wrote his Digest in law French but the work was translated into English for its posthumous publication in 1762.
Baker, J.H. 1989. Manual of Law French. 2d ed. Brookfield, Vt.: Gower.
Hartnick, Alan J. 1994. "The Use of Latin in Law Today." New York State Bar Journal 39 (February).
"Law French." West's Encyclopedia of American Law. . Encyclopedia.com. (January 16, 2019). https://www.encyclopedia.com/law/encyclopedias-almanacs-transcripts-and-maps/law-french
"Law French." West's Encyclopedia of American Law. . Retrieved January 16, 2019 from Encyclopedia.com: https://www.encyclopedia.com/law/encyclopedias-almanacs-transcripts-and-maps/law-french
Modern Language Association
The Chicago Manual of Style
American Psychological Association
"LAW FRENCH." Concise Oxford Companion to the English Language. . Encyclopedia.com. (January 16, 2019). https://www.encyclopedia.com/humanities/encyclopedias-almanacs-transcripts-and-maps/law-french
"LAW FRENCH." Concise Oxford Companion to the English Language. . Retrieved January 16, 2019 from Encyclopedia.com: https://www.encyclopedia.com/humanities/encyclopedias-almanacs-transcripts-and-maps/law-french