Law French:
(17c)

1. The corrupted form of the Norman French language that arose in England in the centuries after William the Conqueror invaded England in 1066 and that was used for several centuries as the primary language of the English legal system; the Anglo-French used in medieval England in judicial proceedings, pleadings, and lawbooks.  Also written law French. -Abbr. L.F.  See NORMAN FRENCH. [1]

     Excerpt from Percy H. Winfield’s The Chief Sources of English Legal History (1925):

     “That Law French was barbarous in its decrepitude does not in the least diminish the value of it to our law when it was full of vitality. It helped to make English law one of the four indigenous systems of the civilized world, for it exactly expressed legal ideas in a technical language which had no precise equivalent.” [2]

     Excerpt from J.H. Baker’s A Manual of Law French (1979):

     “To the linguist, law French is a corrupt dialect by definition.  Anglo-French was in steady decline after 1300.  Lawyers such as Fortescue, on the other hand, were probably serious in maintaining that it was the vernacular of France which was deteriorating by comparison with the pristine Norman of the English courts.  That Fortescue could make such a claim, while living in France, is in itself a clear demonstration that by the middle of the fifteenth century there was a marked difference between the French of English lawyers and the French of France.” [3]

     Excerpt from Bryan A. Garner’s Garner’s Dictionary of Legal Usage (3d ed. 2011):

     “Law French refers to the Anglo-Norman patois used in legal documents and all judicial proceedings from the 12605 to the reign of Edward Ill (1327-1377), and used with frequency in legal literature up to the early 18th century.  When first introduced into England, this brand of French was the standard language used in Normandy; by the 1305, through linguistic isolation, it became a corrupted language — by French standards, at any rate.” [4]

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