The "Great Writ" of habeas corpus is a fundamental right in the Constitution that protects against unlawful and indefinite imprisonment. A writ of habeas corpus is used to bring a prisoner or other detainee (e.g.Our negotiations and settlements experience can significantly impact your case. Call our Houston writs of habeas corpus attorneys at 936-647-1540. Habeas Corpus allows detained or imprisoned individuals to actively challenge the legality of their detention. Application for Writ of Habeas Corpus from Final Felony Conviction (rev. 2018). A federal writ of habeas corpus may address violations of these rights that led to an unfair trial, such as jury tampering or ineffective assistance of counsel. An application for a writ of habeas corpus may only be filed after a final conviction. Definition. Habeas corpus is a fundamental legal instrument safeguarding individual freedom against arbitrary state action. The law in the area is an intricate weave of statute and case law.