Precedent

In common law legal systems, a precedent or authority is a principle or rule established in a previous legal case that is either binding on or persuasive for a court or other tribunal when deciding subsequent cases with similar issues or facts. The general principle in common law legal systems is that similar cases should be decided so as to give similar and predictable outcomes, and the principle of precedent is the mechanism by which that goal is attained. Black's Law Dictionary defines "precedent" as a "rule of law established for the first time by a court for a particular type of case and thereafter referred to in deciding similar cases." common law precedent is a third kind of law, on equal footing with statutory law (statutes and codes enacted by legislative bodies), and regulatory law (regulations promulgated by executive branch agencies).

Stare decisis (Anglo-Latin pronunciation: /ˈstɛəri dɨˈsaɪsɨs) is a legal principle by which judges are obliged to respect the precedent established by prior decisions. The words originate from the phrasing of the principle in the Latin maxim Stare decisis et non quieta movere: "to stand by decisions and not disturb the undisturbed." In a legal context, this is understood to mean that courts should generally abide by precedent and not disturb settled matters.

Case law is the set of existing rulings which made new interpretations of law and, therefore, can be cited as precedent. In most countries, including most European countries, the term is applied to any set of rulings on law which is guided by previous rulings, for example, previous decisions of a government agency--that is, precedential case law can arise from either a judicial ruling or a ruling of an adjudication within an executive branch agency. Trials and hearings that do not result in written decisions of a court of record do not create precedent for future court decisions.