Common law

Common law (also known as case law or precedent) is law developed by judges, courts, and similar tribunals, stated in decisions that nominally decide individual cases but that in addition have precedential effect on future cases. Common law is a third branch of law, in contrast to and on equal footing with statutes which are adopted through the legislative process, and regulations which are promulgated by the executive branch.

A "common law system" is a legal system that gives great precedential weight to common law, so that consistent principles applied to similar facts yield similar outcomes. The body of past common law binds judges that make future decisions, just as any other law does, to ensure consistent treatment. In cases where the parties disagree on what the law is, a common law court looks to past precedential decisions of relevant courts. If a similar dispute has been resolved in the past, the court is usually bound to follow the reasoning used in the prior decision (this principle is known as stare decisis). If, however, the court finds that the current dispute is fundamentally distinct from all previous cases (called a "matter of first impression"), judges have the authority and duty to make law by creating precedent. 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 all common law systems.