An Illinois Subpoena to Testify at a Deposition in a Civil Action is a legal document issued by a court that requires a person to appear in court for the purpose of providing testimony in a lawsuit. It is also known as a deposition subpoena. The subpoena must be served on the witness by a process server, or by certified mail, before the scheduled deposition. The process server must serve the subpoena on the witness in person, or the witness can sign a waiver of service allowing the subpoena to be served by mail. There are two types of Illinois Subpoena to Testify at a Deposition in a Civil Action. The first is the Subpoena Ducks Cecum, which orders the witness to appear and bring certain documents or other evidence related to the case. The second is the Subpoena Ad Testificandum, which orders the witness to appear and testify. Both types of subpoenas require the witness to appear at the specified date, time, and location to provide testimony or produce documents. The witness must comply with the subpoena, or the court can issue a contempt order if the witness fails to comply.