I have serious doubts that this was the correct decision. My worry is not so much about NYC's security, which I think federal authorities and the NYPD should be able to handle. I simply don't believe that the US courts can competently provide justice to these (alleged) terrorists. I'm also not sure that the civilian standards for justice are practical in these circumstances. There are countless examples of standards for our civilian trials that cannot be applied here. For example, our usual rules of evidence might be inappropriate in these cases. Rather than discuss all of them, though, I'm going to focus on just one: the use of an "impartial jury of peers."
First, who, exactly, are KSM's peers? Doesn't the fact that a jury would be made up of US citizens already preclude it from having a balanced "peer group?" Must the jury include Muslims? If so, does their personal version of Islam matter? The detainees religious views are usually on the fringe. Should we have a muslim extremist on the jury? Then, do we have to include people of the racial or ethnic groups of the detainees on the jury? More directly, I don't believe that any group of twelve Americans can really be considered a group of peers of Khalid Sheikh Mohammed.
More critically, though, I don't think any jury in the United States is impartial about figures like KSM. We've been hearing about these cases for years. These detainees have been (probably rightly) demonized for years. Any jury pool you find in the United States will be tainted.
Quite frankly, I believe that a military tribunal, where judgements are made by intelligent people trained to make judgements in these difficult cases, would be more capable of fairly administering justice in these cases. It seems to me that Holder's plan will inevitably lead to either hung juries or, more likely, after these detainees are rightly found guilty, constant legal challenges about the validity of the trials. Honestly, those legal challenges will be the responsible response from lawyers for detainees, because it seems highly unlikely that these trials could possibly meet the standards for fairness we apply to our civilian courts.