The prisoners at Gitmo are enemy soldiers. They were captured on the battlefield bearing arms against US troops. They are not criminals, they didn't commit robbery, murder, rape, arson, or other crimes. They just fought against our soldiers.
No American court, military or civilian is going to convict enemy soldiers just for being enemies. The hundred or so prisoners left in Gitmo need to stay there, otherwise they will go back to fighting for Al Quada. They haven't committed any recognized crimes, but you cannot turn them loose.
US criminal law doesn't recognize prisoner of war. In US jurisprudence, only a court can convict a defendant to jail or worse. Arrests cannot be made until the perp has committed a crime. The Gitmo prisoners haven't committed a crime, haven't been convicted by a court, but we are holding them in jail. There is a good chance that if they were brought to the US, some bat brained judge (we got plenty of those) will order them turned loose. That's why we parked them at Gitmo in the first place.
Just to confuse the issue further, to be a prisoner of war, you have to be a soldier of a recognized nation-state. Al Quada isn't a nation-state, it's a bunch of raghead terrorists. We have international agreements about treatment of prisoners of war. Things like "name, rank, and serial number" mean no interrogation of prisoners of war. So we don't call them prisoners of war, we call them detainees. And we used to interrogate them, harshly, but Obama lacks the stomach for this, so we don't anymore. In fact, Obama has ordered the troops to take no prisoners, kill them all instead.
In short, the Gitmo prisoners need to stay in Gitmo. Giving them trials won't solve anything, it will mostly turn them loose. Bringing them to the US is quite dangerous, some judge may turn them loose.