Illinois Order Habeas Corpus is a legal document issued by the court to free a person from unlawful detention. It is an order issued by a judge that requires a jail or other institution to produce a prisoner before the court and show cause as to why the prisoner is being held. This form of habeas corpus is commonly used in criminal matters as well as civil matters, such as custody disputes. There are two types of Illinois Order Habeas Corpus: an Order of Habeas Corpus Ad-Testificandum and an Order of Habeas Corpus Endurance Lincoln. An Order of Habeas Corpus Ad-Testificandum requires the jail or other institution to produce a prisoner before the court and requires the prisoner to testify. An Order of Habeas Corpus Endurance Lincoln requires the jail or other institution to release the prisoner.