Msi Pries, a law term, which originated as follows. Anciently, nearly all actions in England of any importance were begun and tried before the courts of Westminster. But when the custom began of bringing actions of less value before these courts, and these grew to be numerous, the burden of coming from different and distant parts of England to London became very great; and a practice was introduced some centuries since of beginning a case in Westminster, as the law required, but continuing it from term to term, "unless before" the next term a court which could try the case should be held in the county where the cause of action arose or existed. The record was in Latin; and the words nisi prius (unless before), being the essential part, gave name to the whole procedure. A court of eyre or of assize always did sit in the county in the vacation, and so the case was sure to be tried at home. Practically the phrase "nisi prius court," both in England and the United States, now signifies a court held by one of the judges, or less than a whole bench, usually with a jury, because such was the constitution of the "assize courts before mentioned. Hence the determination of a law question at nisi prius is commonly made by one judge only, and on the spur of the moment.

Many volumes have been published, both in England and the United States, of the decisions made at nisi prius; but they have not the authority of decisions made by the court sitting in banco, both because they are usually the decisions of one judge only, and also because the judges have not had the aid of full argument by counsel.