Common law is a legal system that is largely formed by the decisions previously made by courts and not imposed by legislatures or other government officials. The reasoning used to interpret this type of law is known as casuistry, or case-based reasoning. It is a strict, principle-based reasoning that uses the circumstances of a case to evaluate the laws that are applicable. Decisions that were made about similar cases are valuable, and the case in question is evaluated on the basis of past cases. The strength of the similarity among the cases, in turn, strengthens the reasoning based on them.
The term "common law" also underlines the fact that this type of law did not originate from equity, maritime and other special branches of law. Statutes serve as brief explanations of law and therefore are not very explanatory. Codification is the process by which a statute is passed, expressed within a single document, so that it is understood within existing law rather than creating the need for new laws.
Varies by Jurisdiction
In most cases, common law applies only within that jurisdiction. Judges often create common law by writing opinions about cases that bind lower courts in that jurisdiction. The foundation for this type of law is formed by torts, property and contracts.
English Legal System
In another sense, common law is the basis of the legal system in England and many other English-speaking countries, especially those that were former British colonies, including most of Canada, most of the United States, Hong Kong, the Philippines and Sri Lanka. Common law was invented in England by three courts — King's Bench, Exchequer and the Court of Common Pleas — to establish a system of law that could supersede the judgments of local courts. Also, in terms of its application to civil law, common law was used to compensate people who suffered wrongful civil acts, known as torts.
Not all former British colonies and English-speaking countries have legal systems based on common law. Louisiana, Quebec and South Africa are said to have pluralistic legal systems combining civil, common, customary and religious law. Furthermore, Louisiana and Quebec use French law, and the South African legal system is based on Roman-Dutch law. India uses a mixture of Hindu and English law.