If it can happen to him it can happened to the rest of us. Charge Padilla or set him free.
What "crime" should he be charged with?
He came on a scouting mission. That is not a crime. It does show that he is an enemy combatant --- a spy.
Enemy combatants are not "criminals" They are "enemy combatants". They are dangerous to the country so their "mission" should be interrupted.
It is part of war. People are captured and detained. They are questioned.
Sounds good froma philosophically purist standpoint, but drastic times require drastic measures and extra common sense.
I'll second that.
If they have enough evidence to charge him, then they should do so. If "National Security" concerns are legitimate, then file a motion for a closed hearing and sealed records, but charge him with a crime or turn him loose.