An Illinois Subpoena is a legal document issued by a court or other government agency in the state of Illinois, which requires a person or entity to appear in court or produce relevant documents or records. Subpoenas can be issued to both individuals and businesses, and are usually issued in civil and criminal cases. There are two main types of Illinois Subpoenas: Subpoena Ducks Cecum and Subpoena Ad Testificandum. A Subpoena Ducks Cecum requires a person or company to produce documents or records relevant to the legal case, while a Subpoena Ad Testificandum requires an individual to appear in court and give testimony. In Illinois, both types of Subpoenas must be served in person and must be accompanied by a document called a “return of service” that certifies the document has been served. Failure to comply with an Illinois Subpoena can have severe legal consequences.