The CIU handles all post-conviction reviews, writs of habeas corpus, Chapter 64 motions, and clemency and commutation petitions. The origins of habeas corpus can be traced back to English common law, but it has evolved significantly over the centuries.Federal habeas corpus is a procedure under which a federal court may review the legality of an individual's incarceration. To initiate a state writ of habeas corpus in Texas, a person must first file a petition with the appropriate court. A writ of habeas corpus is a legal tool that a person can use to enforce a superior right of possession to a child. A Writ of Habeas Corpus (Latin for "that you have the body") may be filed on behalf of a person who is unlawfully imprisoned. Please carefully read through all the steps listed below before you begin. In a writ of habeas corpus, a defendant seeks to establish that his or her prison sentence is illegal. This can be done in two ways. It gives judges the power to require law enforcement to justify an arrest.