How long do you have to file a writ of habeas corpus? Find out what this deadline is and what Florida post-conviction motions can extend this time period.Your writ of habeas corpus must state the specific relief you are requesting and the reasons you are requesting it. Habeas corpus is used to challenge the legality of the detention or restraint of a person and to obtain the person's prompt release. Who Should Use This Form. You should use this form if. Writ of Habeas Corpus a civil case number and assign it to the judge assigned to the pending writ with the lowest case number. The "Great Writ" of habeas corpus is a fundamental right in the Constitution that protects against unlawful and indefinite imprisonment. Article 1, Section 13 of the Florida Constitution provides: "The writ of habeas corpus shall be grantable of right, freely and without cost. This petition, called a writ of Habeas Corpus, is filed in Federal Court (US District Court ) whether you are serving time in a federal or state prison.