A common law legal system is characterized by case law developed by judges, courts, and similar tribunals, when giving decisions in individual cases that have precedential effect on future cases.[2][3][4][5] The body of past common law binds judges deciding later cases to ensure consistent treatment and so that consistent principles applied to similar facts yield similar outcomes.[6] In common law cases, where the parties disagree on what the law is, the court is usually bound to follow the reasoning used in past decisions of relevant courts. If the court finds that the current dispute is fundamentally distinct from previous cases, judges have the authority and duty to make law by creating precedent.[7] Thereafter, the new decision becomes precedent, and will bind future courts. 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 common law systems, but connotations of the term "common law" vary according to context, both in present-day use and historically.
Common law originated during the Middle Ages in England,[8] and from there was propagated to the colonies of the British Empire, including India,[9] the United States (both the federal system and all, except Louisiana, of the 50 states), Pakistan,[10] Nigeria, Bangladesh, Canada (and all its provinces except Quebec), Malaysia, Ghana, Australia,[11][12] Sri Lanka, Hong Kong, Singapore, Burma, Ireland, New Zealand, Papua New Guinea, Jamaica, Trinidad and Tobago, Cyprus, Barbados,[13] South Africa, Zimbabwe, Cameroon, Namibia, Liberia, Sierra Leone, Botswana, Guyana, and Fiji. Today, one third of the world's population live in common law jurisdictions or in systems mixed with civil law.
The development of case law in common law jurisdictions relies on the publication of notable judgments in the form of law reports for use by lawyers, courts and the general public, including those judgments which, when delivered or later, are accepted as being "leading cases" or "landmark decisions".[14] The records, commentaries, writings by jurists and historians, and text-books on pleading,[15] show that from the establishment of the common law courts in the thirteenth century to statutory reforms in the nineteenth century, the development of case law was constrained by the common law "forms of action".
