Common Law & The Rise of Justices

William, duke of Normandy, conquers England in 1066 and maintains Anglo-Saxon law. Eyres, or justices, are appointed by the William's court to help bring a central political authority to the countryside. Their responsibility is to ensure that officials do their duty according to the existing laws, leaving the shires well governed and limiting the opportunity for local leaders to challenge the new king. During this time, community rules and customs serve as unwritten legal precedents and inform judicial reasoning. The judges formally criminalize actions — like murder, rape, arson, and burglary — that were previously regarded as private disputes. The growing body of decisions begins to shape a national legal system based on common law. The first book of the English common law, Tractatus de legibus et consuetudinibus regni Angliae (Treatise on the Laws and Customs of the Kingdom of England) is written in the 1180s. It is usually attributed to Ranulf de Glanville, chief justice during the reign of King Henry II. With its origins in early English society, common law is often considered the major source of modern criminal law in the United States.

Battle of Hastings
Battle of Hastings Bayeux Tapestry, c.1066