The cons utionality of part or all of that act is still a big unknown. As seen in the illegal suspension of the Habeas Corpus (Boumediene v. Bush and Al Odah v. United States), later on turned over by the Supreme Court, it can take just as many years and can also be stalled.
Not to mention that the wording on the Act is counterproductive and already caused cases to be entirely dismissed because of it:
On June 4, 2007, in two separate cases, military tribunals dismissed charges against detainees who had been designated as "enemy combatants" but not as "unlawful enemy combatants". The first case was that of Omar Khadr, a Canadian who had been designated as an "enemy combatant" in 2004. Khadr was accused of throwing a grenade during a firefight in Afghanistan in 2002. Colonel Peter Brownback ruled that the military tribunals, created to deal with "unlawful enemy combatants," had no jurisdiction over detainees who had been designated only as "enemy combatants." He dismissed without prejudice all charges against Khadr. Also on June 4, Captain Keith J. Allred reached the same conclusion in the case of Salim Ahmed Hamdan.
This monstrosity is probably going to be abolished and remembered just like it's cousins, the
Alien and Sedition Acts
I actually have no problem trying these people in military tribunals under military law (the same used to deal with spies in the Cold War era).
The problem is that military law actually grants a good amount of rights also, as it should, of due process. Things like discovery of evidence, and the accused being able to examine and defend himself against the accusations.
Obviously, guys like didn't want to take any chances, and came up with the MCA.
The fairly recent 2009 amendment to the act actually works around some of those mishaps for defendants, but still falls short of the due process provided by both the standard military trials and civilian trials.