Throughout Europe in the twelfth and thirteenth centuries, the law was a hodgepodge of customs, feudal rights, and provincial practices. Rulers wanted to blend these elements into a uniform system of rules acceptable and applicable to all their peoples, though their success in doing so varied.

The French king Louis IX (r. 1226–1270) was famous for his concern for justice. Each French province, even after being made part of the kingdom of France, retained its unique laws and procedures. But Louis IX created a royal judicial system, establishing the Parlement of Paris, a kind of supreme court that heard appeals from lower courts.

Under Henry II (r. 1154–1189), England developed and extended a common law — a law common to and accepted by the entire country, unique in medieval Europe. Henry’s son John (r. 1199–1216), however, met with serious disappointment after taking the throne. A combination of royal debt, increased taxation, and military failures fed popular discontent. A rebellion begun by northern barons grew, and in 1215 the barons forced him to attach his seal to the Magna Carta — the “Great Charter,” which became the cornerstone of English justice and law. The Magna Carta was simply meant to assert traditional rights enjoyed by certain groups, but in time it came to signify the broader principle that everyone, including the king and the government, must obey the law.

Statements of legal principles such as the Magna Carta were not how most people experienced the law in medieval Europe. Instead they were involved in actual cases. Judges determined guilt or innocence in a number of ways. In some cases, they ordered a trial by ordeal, in which the accused might be tied hand and foot and dropped in a lake or river. People believed that water was a pure substance and would reject anything foul or unclean. Thus a person who sank was considered innocent, while a person who floated was found guilty. Trials by ordeal were relatively rare, and courts increasingly favored more rational procedures, in which judges heard testimony, sought witnesses, and read written evidence if it was available.