A deposition in the law of the United States, or examination for discovery in the law of Canada, is the taking of sworn, out-of-court oral testimony of a witness that may be reduced to a written trans
Expert witness deposition in a mock trial simulation. The court reporter, who is an officer of the court, administers the oath to the deponent.
Example page from stenographers copy of an expert's deposition from Anderson v. Cryovac
A subpoena ad testificandum is a court summons to appear and give oral testimony for use at a hearing or trial. The use of a writ for purposes of compelling testimony originated in the ecclesiastical
Deposition (law)
…subpoena duces tecum subpoena ad testificandum Section 1782 Discovery…
Prior to the Fourth Lateran Council, the norm was trial by ordeal.
Pope Innocent III was indirectly responsible for the use of subpoena when trial by ordeal was outlawed by the Fourth Lateran Council
John Fortescue (judge) gives a picture of modern-form jury trials.
Early juries might consist of twenty-four knights. Later maintenance and corruption became problematic.