In 1066, William the Conqueror came across the English Channel from what is now France and conquered the land that is today called England. The conquering Normans spoke French, and their language became the language of the law. For several centuries after, lawyers and judges in English courts spoke French. English courts continue to use many French words, which means that American legal opinions also use French words, including: plaintiff, defendant, tort, contract, crime, judge, attorney, counsel, court, verdict, party, appeal, evidence, and jury.
Kerr, Orin S. “How to Read a Legal Opinion.” The Green Bag 2nd 11.1 (2007): 51-63.