In law, common law (also known as judicial precedent, judge-made law, or case law) is the body of law created by judges and similar quasi-judicial tribunals by virtue of being stated in written opinions.
The defining characteristic of common law is that it arises as precedent. Common law courts look to the past decisions of courts to synthesize the legal principles of past cases. Stare decisis, the principle that cases should be decided according to consistent principled rules so that similar facts will yield similar results, lies at the heart of all common law systems. If a court finds that a similar dispute to the present one has been resolved in the past, the court is generally bound to follow the reasoning used in the prior decision. If, however, the court finds that the current dispute is fundamentally distinct from all previous cases (a "matter of first impression"), and legislative statutes are either silent or ambiguous on the question, judges have the authority and duty to resolve the issue. The opinion that a common law judge gives agglomerates with past decisions as precedent to bind future judges and litigants.
The common law, so named because it was "common" to all the king's courts across England, originated in the practices of the courts of the English kings in the centuries following the Norman Conquest in 1066. The British Empire later spread the English legal system to its colonies, many of which retain the common law system today. These common law systems are legal systems that give great weight to judicial precedent, and to the style of reasoning inherited from the English legal system.
The term "common law", referring to the body of law made by the judiciary, is often distinguished from statutory law and regulations, which are laws adopted by the legislature and executive respectively. In legal systems that follow the common law, judicial precedent stands in contrast to and on equal footing with statutes. The other major legal system used by countries is the civil law, which codifies its legal principles into legal codes and does not treat judicial opinions as binding.
Today, one-third of the world's population lives in common law jurisdictions or in mixed legal systems that combine the common law with the civil law, including Antigua and Barbuda, Australia, Bahamas, Bangladesh, Barbados, Belize, Botswana, Burma, Cameroon, Canada (both the federal system and all its provinces except Quebec), Cyprus, Dominica, Fiji, Ghana, Grenada, Guyana, Hong Kong, India, Ireland, Israel, Jamaica, Kenya, Liberia, Malaysia, Malta, Marshall Islands, Micronesia, Namibia, Nauru, New Zealand, Nigeria, Pakistan, Palau, Papua New Guinea, Philippines, Sierra Leone, Singapore, South Africa, Sri Lanka, Trinidad and Tobago, the United Kingdom (including its overseas territories such as Gibraltar), the United States (both the federal system and 49 of its 50 states), and Zimbabwe.
Definitions
The term common law has many connotations. The first three set out here are the most-common usages within the legal community. Other connotations from past centuries are sometimes seen and are sometimes heard in everyday speech.
Common law as opposed to statutory law and regulatory law
The first definition of "common law" given in Black's Law Dictionary, 10th edition, 2014, is "The body of law derived from judicial decisions, rather than from statutes or constitutions; [synonym] CASELAW, [contrast] STATUTORY LAW". This usage is given as the first definition in modern legal dictionaries, is characterized as the "most common" usage among legal professionals, and is the usage frequently seen in decisions of courts. In this connotation, "common law" distinguishes the authority that promulgated a law. For example, the law in most Anglo-American jurisdictions includes "statutory law" enacted by a legislature, "regulatory law" (in the U.S.) or "delegated legislation" (in the U.K.) promulgated by executive branch agencies pursuant to delegation of rule-making authority from the legislature, and common law or "case law", i.e., decisions issued by courts (or quasi-judicial tribunals within agencies). This first connotation can be further differentiated into:
Publication of decisions, and indexing, is essential to the development of common law, and thus governments and private publishers publish law reports. While all decisions in common law jurisdictions are precedent (at varying levels and scope, as discussed throughout the article on precedent), some become "leading cases" or "landmark decisions" that are cited especially often.