An Illinois Subpoena is a legal document issued by the court in the State of Illinois to compel a witness to appear in court and give testimony, produce documents, or both. There are two types of Illinois Subpoenas: a Subpoena Ducks Cecum, which requires the witness to bring documents to court, and a Subpoena Ad Testificandum, which requires the witness to appear and testify. An Illinois Subpoena must be served to the witness by a sheriff or another authorized process server, and the witness must be given reasonable notice before the court appearance. Failure to comply with an Illinois Subpoena can result in severe legal consequences.