In France, this effort to create a royal judicial system was launched by Louis IX (r. 1226–1270). Each French province, even after being made part of the kingdom of France, had retained its unique laws and procedures, but Louis IX published laws for the entire kingdom and sent royal judges to hear complaints of injustice. He established the Parlement of Paris, a kind of supreme court that heard appeals from local administrators and regional courts, and also registered (or announced) royal laws. By the very act of appealing the decisions of local courts to the Parlement of Paris, French people in far-flung provinces were recognizing the superiority of royal justice.

In the Holy Roman Empire, justice was administered at multiple levels. The manorial or seigneurial court, presided over by the local lay or ecclesiastical lord, dealt with such matters as damage to crops and fields, trespass, boundary disputes, and debt. Dukes, counts, bishops, and abbots possessed authority over larger regions, and they dispensed justice in serious criminal cases there. The Holy Roman emperors established a court of appeal similar to that of the French kings, but in their disunited empire it had little power.

England also had a variety of local laws with procedures and penalties that varied from one part of the country to another. Henry I occasionally sent out circuit judges, royal officials who traveled a given circuit or district, to hear civil and criminal cases. Henry II (r. 1154–1189) made this way of extending royal justice an annual practice. Every year royal judges left London and set up court in the counties. These courts regularized procedures in civil cases, gradually developing the idea of a common law, one that applied throughout the whole country. Over the next two or three centuries common law became a reality as well as a legal theory. Common law relied on precedent: a decision in an important case served as an authority for deciding similar cases. Thus written codes of law played a less important role in England than they did elsewhere. (This has continued to today; in contrast to the United States and most other countries, the United Kingdom does not have a written constitution.)

Henry also improved procedure in criminal justice. In 1166 he instructed the sheriffs to summon local juries to conduct inquests and draw up lists of known or suspected criminals. These lists, or indictments, sworn to by the juries, were to be presented to the royal judges when they arrived in the community. This accusing jury is the ancestor of the modern grand jury. Gradually, in the course of the thirteenth century, the king’s judges adopted the practice of calling on twelve people (other than the accusing jury) to consider the question of innocence or guilt; this was the forerunner of the trial jury.

One aspect of Henry II’s judicial reforms encountered stiff resistance from an unexpected source. In 1164 Henry insisted that everyone, including clerics, be subject to the royal courts. The archbishop of Canterbury Thomas Becket, who was Henry’s friend and former chief adviser, vigorously protested that church law required clerics to be subject to church courts.

The disagreement between king and archbishop dragged on for years. Late in December 1170, in a fit of rage, Henry expressed the wish that Becket be destroyed. Four knights took the king at his word. They rode to Canterbury Cathedral and, as the archbishop was leaving evening services, murdered him, slashing off the crown of his head and scattering his brains on the floor of the cathedral. The assassination of an archbishop turned public opinion in England and throughout western Europe against the king, and Henry had to back down. He did public penance for the murder and gave up his attempts to bring clerics under the authority of the royal courts. Miracles were recorded at Becket’s tomb; Becket was made a saint; and in a short time Canterbury Cathedral became a major pilgrimage and tourist site.