What term is used for the court order that requires witnesses to testify in court?

The term used for the court order that requires witnesses to testify in court is "subpoena." A subpoena is a legal document issued by a court that commands an individual to appear at a specified time and place to provide testimony or produce evidence. This is essential in legal proceedings to ensure that relevant witnesses are available to provide their accounts, which can significantly influence the outcome of a case.

While a deposition is a process where witnesses provide sworn testimony outside of court, an affidavit is a written statement made under oath, generally used to present evidence in a written form rather than requiring live testimony. A summons, on the other hand, is a legal notice to a defendant or respondent to appear before the court but does not specifically compel a witness to testify. Thus, "subpoena" accurately captures the court order needed to mandate a witness's presence for courtroom testimony.