in law, a judicial writ which lies in cases where the jury being impannelled and returned before the justices of the bank, one of the parties requests to have such a writ, for the ease of the country, in order that the trial may come before the justices in the same county on their coming thither. The purport of a writ of nisi prius is, that the sheriff is thereby commanded to bring to Westminster the men impannelled, at a certain day, before the justices, "nisi prius justiciarii domini regis ad affias capiendas venerint."