1911 Encyclopædia Britannica/Amicus Curiae

AMICUS CURIAE (Lat. for “a friend of the court”), a term used primarily in law, signifying a person (usually a member of the bar) who, having special knowledge but not being engaged in the suit, intervenes during its hearing to give information for the assistance of the court, either upon some fact relevant to the issue or upon a point of law, such as the hearing of a local custom, the precedent of some decided case, &c.