Legal English the history of the development of English as a legal language. In prehistoric Britain, traditional common law was discussed in the vernacular (see Celtic law). The legal language and legal tradition changed with waves of conquerors over the following centuries. Roman Britain (after the conquest beginning in AD 43) followed Roman legal tradition, and its legal language was Latin. Following the Roman departure from Britain circa 410 and the Anglo-Saxon invasion of Britain, the dominant tradition was instead Anglo-Saxon law, which was discussed in the Germanic vernacular (Anglo-Saxon, Old English), and written in Old English since circa 600, beginning with
Anglo-Norman language century, intermarriages with English nobility became more frequent. French became progressively a second language among the upper classes. Moreover, with the Hundred Years' War and the growing spirit of English nationalism, the status of French diminished. French was the mother tongue of every English king from William the Conqueror (1066-1087) until Henry IV (1399–1413). Henry IV was the first to take the oath in English, and his son, Henry V (1413–1422), was the first to write in English. By the end of the 15th century, French became the second language of a cultivated elite. Until the end of the 13th