The "Great Writ" of habeas corpus is a fundamental right in the Constitution that protects against unlawful and indefinite imprisonment. A person who believes she is being imprisoned illegally can file a petition asking a judge to issue a writ of habeas corpus.Habeas corpus means "you have the body" and is an important civil right, even if it sounds archaic. Learn how habeas corpus works. Latin, meaning "you have the body. Federal habeas corpus is a procedure under which a federal court may review the legality of an individual's incarceration. The writ of habeas corpus is often called the 'great writ' because of its importance in safeguarding individual freedom. How to File Habeas Corpus and Compassionate Release David is a law school graduate and former practicing attorney. In sum, the writ of habeas corpus should encompass a challenge to a prisoner's conditions of confinement. Petition in the superior court, you should file it in the county that made the order.