Habeas corpus refers to the principle of freedom from unlawful detention. This section constitutes an overview on California habeas corpus practice as it relates to the handling of criminal appeals.You will file a Habeas Corpus petition in California if you are arguing that your conviction violated a state law, or that a California law is unconstitutional. A habeas corpus petition in California allows you to challenge your conviction or sentencing. You can file it only after exhausting all criminal appeals. This following portions of this manual contain a step-by-step guide to California state habeas corpus process, including court forms and sample court pleadings. This petition must be clearly handwritten in ink or typed. You should exercise care to make sure all answers are true and correct. Habeas petitions provide prisoners whose rights are being violated with a means of requesting assistance from a judge. The law in the area is an intricate weave of statute and case law.