An Illinois Subpoena To Testify is a legal document issued by a court in the state of Illinois that requires a person to appear in court and testify as a witness. This document is used when a witness is needed to give evidence or to provide further clarification on a case. The subpoena can be issued by either a judge or a clerk of the court, and must include the name of the witness, the time and date of the appearance, and the location of the court. There are two types of Illinois Subpoena To Testify: a Subpoena Ducks Cecum, which requires the witness to bring specified documents to court, and a Subpoena Ad Testificandum, which requires the witness to appear and testify in court.