The government does not want to try five alleged 9/11 conspirators still at Guantanamo because there would be further revelations of U.S. torture and other illegality. From Andrew P. Napolitano at lewrockwell.com:
Last week, the government announced that it does not want to try Khalid Shaikh Mohammed and four of his colleagues whom it claims are the remaining conspirators of the attacks on 9/11.
All five are awaiting trial at the U.S. Naval Base in Guantanamo Bay, Cuba. The allegations are that these five conspired to commit mass murder, a capital offense. Even though conspiracy is not a war crime, the feds are planning to try these defendants before a military tribunal under the rules utilized in federal criminal trials.
All five were detained from around 2003 to 2006 at CIA black sites, where they were kept in solitary confinement and egregiously tortured. After the CIA torture was concluded, the five were transferred to military custody at Gitmo in 2006.
There, the tortures resumed until FBI agents arrived to interrogate them. For all of its faults in other cases, the FBI put a stop to the military torture and solitary confinement.
The decisions to have the CIA torture these detainees, not to charge them with capital offenses in federal district courts in the U.S. as the Constitution mandates, to implement military torture, to charge these folks with crimes not recognized under the laws of war before military tribunals, to scuttle the constitutionally mandated jury system, and to keep the Department of Justice out of these cases were all made by the legally ignorant, Constitution-defying President George W. Bush.