What are we trying to prove by giving war criminals civil trials? And to who?

 I’m not entirely sure this is the correct forum for what I’m about to write, but I need to put it out there as a kind of “sanity check” for myself.  I’ll thank you in advance for indulging me…

 The Justice Department is bringing five terrorists from the US Detention center in Cuba to NYC to stand trial in a civilian court steps from the site of the September 11th attacks.
 
 When questioned about the decision, Attorney General Eric Holder essentially stated that we should not be concerned because they would definately be convicted.

 So the Amercian Government is having a trial for these people with the understanding from the onset that they will be found guilty.

 I personally feel that these folks have no right to set foot in this country at all, let alone two blocks away from Ground Zero.  I truly feel that a Military Tribunal should have already put them in the ground.

However,  I also don’t fully understand the logic in having a trial where we state at the onset that they will be found guilty as some sort of example of the superiority of our legal system.

 The basis of that system is that you are innocent until proven guilty. This is not the case here. So what exactly are we trying to prove; and to who?

 It’s like having an election because you know your guy will win. An empty gesture to promote the illusion of democracy? 

 Is this really where we’re headed?  Am I missing something?