Only people in custody under the sentence of a Federal court may file motions pursuant to 28 U.S.C. 2255 to vacate their convictions or sentences. A Writ of Habeas Corpus is a motion which is filed most frequently to ensure that a Defendant's imprisonment or detention is not illegal.The Writ of Habeas Corpus demands that requires a prisoner must go before the court to determine if there is lawful authority to detain the prisoner. Habeas corpus is a kind of petition that you can file in federal court to claim that your imprisonment violates federal law. Though subject to different rules, incarcerated people in both state or federal custody may petition for a federal writ of habeas corpus. What Is Habeas Corpus? Instructions to complete the forms and steps in the process. 5. 5. Attorneys in the CHU represent persons under a sentence of death in habeas corpus proceedings in the federal court. Who May Use This Form. As in a direct appeal, the Court may affirm, modify or reverse the original decision.