An Illinois Subpoena for Deposition is a court order issued by a court in the state of Illinois to compel a witness to appear at a deposition or trial. It requires the person to answer questions under oath and to produce documents or other evidence related to the case. There are two types of Illinois Subpoena for Deposition: a subpoena duces tecum, which requires the witness to produce documents and other physical evidence, and a subpoena ad testificandum, which requires the witness to answer questions. Both types of subpoenas can be issued by the court, a lawyer, or any other person authorized by law.