A writ of habeas corpus is a legal tool that a person can use to enforce a superior right of possession to a child. Please carefully read through all the steps listed below before you begin.Notary fills out below. A writ of habeas corpus is a legal order that commands an individual or entity to produce a person who is allegedly being detained unlawfully. In child custody cases, parents or guardians can use the writ of habeas corpus to contest the legality of custody arrangements. This is a request to the court for the. This guide includes forms and instructions for a letter and affidavit to request that the court register an outofstate custody order in Texas. In Texas child custody cases, a parent may file a Habeas Corpus writ if the other parent is violating a custody order. In Texas child custody cases, a parent may file a Habeas Corpus writ if the other parent is violating a custody order. Coming up with a child custody agreement that a couple that is undergoing a divorce can agree with is not easy.