A writ of habeas corpus allows you to make arguments that you can't make in an appeal. The Habeas Corpus petition claims the arrest, sentence, or trial violated constitutional law, making imprisonment unlawful.The writ of habeas corpus is a legal order requiring a person holding another person to produce that individual before a court or judge. The privilege of the writ of habeas corpus shall not be suspended except in cases of rebellion or invasion when the public safety may require it. A habeas petition is used when one is contesting the validity of their sentence or conviction. Most people have heard of the Writ of Habeas Corpus, which is literally a plea to release the body of a person being detained. 9th, 1936), the court stated it was "with- out power" to appoint an attorney for a habeas corpus petitioner. Filed in the federal habeas corpus petition. The Illinois Supreme Court is the highest court in the State. The law in the area is an intricate weave of statute and case law.