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 English dialects by Viking settlement. The same word had been established in Normandy by the Normans (Norsemen) and was then brought over after the Conquest and established firstly in southern English dialects. It is, therefore, argued that the word "mug" in English shows some of the complicated Germanic heritage of Anglo-Norman. Many expressions used in English today have their origin in Anglo-Norman (such as the expression "before-hand" derives from Anglo-Norman "avaunt-main"), as do many modern words with interesting etymologies. "Mortgage", for example, literally meant "death-wage" in Anglo-Norman. "Curfew" (fr. "couvre-feu") meant "cover-fire", referring to the time in the evening when