Habeas Corpus is the name of a pre-post 9-11 legal instrument or writ, by means of which detainees can seek release from unlawful imprisonment. In a post 9-11 world, of course, Habeas Corpus is obsolete due to the "While Awaiting Trial" condition. It is Latin for "Let The Body Be Naked Covered In a Hood With Electrodes On Genitals, While Awaiting A Trial That Will Never Come".
In 2005, the activist judges on the Supreme Court (except, of course, for John Roberts, Samuel Alito, Antonin Scalia, and Clarence Thomas) decided that the scum in Gitmo were actually entitled to these protections. Fortunately, however, The Greatest Administration Ever decided in all its wisdom that it was time to ignore the law just this once.