Common law

Common law is a system of judge-made law that began in the royal courts of medieval England and was later adopted by many former British colonies. In the 1100s, King Henry II set up traveling judges who handled cases and applied a uniform set of rules across the country. Over time, the decisions of these judges created precedents that built into a detailed legal system, which served as England’s primary method of lawmaking for centuries. Today, the term “common law” refers both to this historically English system—where judges can create binding rules for future courts—and to the body of laws that result from it.

Compared to the civil law tradition found in much of continental Europe, common law has less direct influence from Roman law and is less likely to be codified into comprehensive codes. This gives common law judges more freedom in interpreting statutes and a quasi-legislative role when deciding cases. Still, some countries, like South Africa and Scotland, have mixed systems that blend common law and civil law elements. Common law also differs from other types of valid law, such as statutes, equity, and religious laws like canon law or sharia.

Today, about one-third of the world’s population lives in common law jurisdictions or mixed legal systems. These include Australia, Bangladesh, Canada, Hong Kong, India, Ireland, Nigeria, Pakistan, Singapore, and the United States.

The term “common law” has several related meanings. First, after the Norman Conquest, it meant the law common to the king’s courts, as opposed to local courts. Second, it became synonymous with judge-made law, distinct from statutory law. Third, as the British Empire expanded, colonies that adopted common law procedures were called common law systems, to distinguish them from civil law systems. Fourth, in the late medieval period, England developed a separate system of equity administered by the Court of Chancery; even in jurisdictions that later merged the two court systems, equity remains a distinct set of rules separate from common law. Fifth, England still has ecclesiastical courts with jurisdiction over certain religious matters, and “common law” can refer to laws outside those courts.

Originally, common law referred to the laws common to all the king’s courts across England, which grew out of practices in those courts after the Norman Conquest in 1066. This was different from the local folk courts of shires and hundreds, where most disputes were settled before the Conquest. Even after 1066, other courts existed—urban boroughs, merchant fairs, and manorial or seigniorial courts held by large landowners.

In the 1100s and 1200s, continental European countries began adopting Roman law doctrines and civil codes, like the Corpus Juris Civilis. But England already had its common law system, so common law jurisdictions often differ from civil law ones in judicial reasoning and sources of law. Some places, like Louisiana and parts of Canada, have fused systems with both civil and common law elements. Despite their differences, the two systems have influenced each other. Early common law judges and scholars, such as Glanvill and Bracton, were familiar with Roman law—many were clerics trained in canon law. Bracton’s treatise *De Legibus et Consuetudinibus Angliae* was heavily shaped by canon law and Justinian’s *Institutes*, and later influenced Blackstone’s *Commentaries on the Laws of England*. Roman law ideas regained importance in common law scholarship with the rise of academic law schools in the 1800s. Today, major legal divisions like property, contract, tort, and unjust enrichment appear in both systems. Common law countries are increasingly adopting codes in areas like bankruptcy, intellectual property, antitrust, banking regulation, securities, and tax law. A major example is the Uniform Commercial Code in the United States, created by the American Law Institute and Uniform Law Commission, now enacted in most U.S. states and territories, including the District of Columbia.

Starting in the 1400s, litigants who felt wronged by common law courts began petitioning the king for relief. This eventually led to the development of equity, administered by the Court of Chancery, as a separate body of law.