Common law

The common law is a legal system built on rulings made by judges, tracing its roots to the royal courts of medieval England. It was later adopted by many territories that were once part of the British Empire.

In the 1100s, King Henry II sent traveling judges across England to hear cases and apply a uniform set of rules. Over time, the decisions of these judges created precedents, forming a detailed body of common law that served as England’s primary method of lawmaking for centuries. Today, the term “common law” can refer both to this historically English system—where judges can create binding rules for future courts—and to the actual collection of laws that such systems produce.

Laws common to all England

Compared to the civil law tradition found in much of continental Europe, common law shows less influence from Roman law and is less likely to be written into comprehensive codes. This gives common law judges broader freedom when interpreting statutes, effectively allowing them to make law through their rulings. However, 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.

Roughly a third of the world’s population now lives under common law or mixed legal systems. Examples include Australia, Bangladesh, Canada, Hong Kong, India, Ireland, Nigeria, Pakistan, Singapore, and the United States.

Definition and terminology

The term “common law” carries several related meanings. First, after the Norman Conquest, it referred to the law shared by 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 grew, colonies that adopted common law procedures were called common law systems, in contrast to civil law ones.

Fourth, during the late medieval period, England developed a separate set of equitable rules administered by the Court of Chancery. Even in jurisdictions that later merged these two court systems, equity remains a distinct body of rules separate from the common law. Fifth, England still has ecclesiastical courts with authority over certain religious matters, and “common law” can describe the laws that are not part of those church courts.

Originally, common law meant the laws common to all of the king’s courts in England, stemming from the practices of those courts after the Norman Conquest in 1066. This sense of common law is distinct from the local folk courts of shires and hundreds, where most disputes were settled before the Conquest. Even after 1066, other courts continued to exist, such as those in boroughs, merchant fairs, and the manorial courts of large landowners.

During the 1100s and 1200s, continental European countries began adopting Roman law doctrines, including codified civil codes like the Corpus Juris Civilis. England, however, already had its common law system, so common law jurisdictions often differ significantly from civil law ones in judicial reasoning and sources of law. Still, some places, like Louisiana and parts of Canada, have fused systems combining both traditions.

Despite their differences, the two systems have influenced each other over time. Early English judges and scholars like 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 the structure of 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.

As a result, today the main divisions of law—property, contract, tort, and to some extent unjust enrichment—appear in both civil and common law systems. Common law countries are also increasingly adopting codes in areas like bankruptcy, intellectual property, antitrust, banking regulation, securities, and tax law. A major example is the Uniform Commercial Code (UCC) in the United States, created by the American Law Institute and Uniform Law Commission, which has been enacted, with local variations, in most U.S. states and territories, including the District of Columbia.

Law and equity

By the 1400s, litigants who felt wronged by the common law courts began petitioning the king for relief. This practice eventually led to the development of equity, administered by the Court of Chancery.