In reality, the prime reason the Bush administration is invoking national security is to conceal the crimes that have been committed under executive order and to protect itself from political and legal blowback. Above all, the hearings are being held in secret because of what the detainees could reveal about the illegal CIA "gulag" authorized by Bush. ...

The nature of the tribunals is made clear by the fact that the government is willing to consider evidence obtained by torture, deny the right to counsel, bar the public witness of the press and redact hearing transcripts. All of this is aimed at designating prisoners as enemy combatants, a category concocted by the Bush administration for the express purpose of circumventing democratic and constitutional rights. ...

Human Rights Watch background on some of the prisoners previously held by the CIA who now face status review hearings can be found here: http://www.hrw.org/backgrounder/usa/us1004/7.htm