common law

law which is determined by judges, method of lawmaking that began in England; unwritten law, law that is based on past legal decisions

In common law legal systems, the law is created and/or refined by judges: a decision in the case currently pending depends on decisions in previous cases and affects the law to be applied in future cases. When there is no authoritative statement of the law, common law judges have the authority and duty to "make" law by creating precedent. The body of precedent is called "common law" and it binds future decisions. In future cases, when parties disagree on what the law is, an "ideal" common law court looks to past precedential decisions of relevant courts. If a similar dispute has been resolved in the past, the court is 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, it will decide as a "matter of first impression." Thereafter, the new decision becomes precedent, and will bind future courts under the principle of stare decisis.
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A judge-made law that originated in England from the decisions shaped according to prevailing custom. Decisions were reapplied to similar situations and, thus, gradually became common to the nation.

Judge-made law. Law which exists and applies to a group on the basis of historical legal precedents developed over hundreds of years. - (read more on Common law)