Nisi Prius Definition: Latin: a civil jury trial. Related Terms: Jury, Juror Strictly, nisi prius translates to "unless before" but it has obtained a distinct meaning in the common law. Rapalje and Lawrence:"In the practise of the English High Court, a trial nisi prius is where an action is tried by a jury before a single judge...."REFERENCES:Rapalje, Stewart and Lawrence, Robert, A Dictionary of American and English Law, Volume II (Jersey City: Frederick D. Linn & Co. Law Publishers and Booksellers, 1883), page 869. Categories & Topics: Dictionary of Latin Law Terms Find you are constantly looking up definitions? Try our search provider (works in most modern browsers) If you find an error or omission in Duhaime's Legal Dictionary, or if you have legal term suggestion, we'd love to hear from you!