Law review article on the constitutionality of the military commission

[Gene C]

To me this seems like an obvious, open-and-shut case: You don't haul civilians into a military court when civilian courts are open and functioning.

Functioning - yes
Able to handle this case - no

The circumstances of Lincoln's assassination as Commander in Chief following a bloody civil war justified a military trial.
Personally I doubt todays civilian courts are capable of handling a similar situation.