The ideal of indefinite detentions raises alarm bells in some ears. Some think that the treatment of the Gitmo prisoners could be a model, which could later be used for how to handle the government's own dissent citizens, and therefore a very dangerous precedent could be established.
Moreover -- How can you put people on trial who were captured on the battlefield? In a foreign country? Engaged in the bloody business that soldiers do? In this case defending / fighting for that country? Many believe that you shouldn't / mustn't.
The best of these 'trials" become events for show, to justify the government's actions for detaining people, 'Cooperating' defendants are compelled / forced to confess guilt to received 'lenient' sentences.
Oh yeah, the coerced confessions aid the government's PR, gives it stuff to spin about how what it's doing is 'legal'. Not only it is not legal and not right, it is not legit.
If this government ignores proper legal procedures, believing itself endowed by the Almighty to create its own procedures, then others will do so too.
IMHO, there is a way of treating the Gitmo prisoners without the U.S. raising the bogeyman -- of? Some new world order?
The government could extend to the Gitmo prisoners the protection of history, and declared them to be what they are, Prisoners of War, and grant them the status of POW. They are prisoners of the U.S. war in Iraq and Afghanistan, and on the War on terror, the war with al Qaeda, POW's are held until hostilities are over, when ever that is.
The government's order of indefinite detainment strikes some as a means for the wholesale and unlawful detainment of people whom the government may want to detain.