lawyerfag here. Military tribunals have only limited application to US citizens in the US. The reason Gitmo is outside of the US is that it removed US legal jurisdiction from the equation for american enemy combatants.
Under martial law, the military operates the police, courts, and legislature instead of the civilian government.
In any event, all trials are subject to the Uniform Code of Military Justice , found here: http:// www.ucmj.us/
Although a person held under Marshal Law detention cannot challenge his detention, rules of trials still remain.