There is no need to quote the Constitution, or even read it. Those in Washington don't refer to it anymore.
...or many FReepers, for that matter. It's all about power. "We" have it, so there.
But the very best view of the Constitution is that of the Founders.
Consider the impressive Constitutional protections Padilla does have: Habeas Corpus- he can have a court decide if he is justly held as a combatant,
Due process- he can have a court decide if he was fairly treated under the rules congress, or the executive if congress hasn't, provided, Most important- his detention is over when the congressional authorization of military force is over: no military force means no military detainees ( as surely as authorizing military force authorizes military detainees).
I think the Founders have reserved as much liberty to us as they dared.
I suspect that they did not give this power of trying crimes under the laws of nations to the courts because they feared if in times of great danger the law no longer protected the people then they will take the law into their own hands, and the Republic will be over.
In today's circumstances imagine the reaction in the people if the release of a terrorist on a technicality allowed him to take part in a horrible attack!
The mob would be loose!
I'll try to find some Founder's remarks from the Founding documents and ratification conventions that might shed some light on this.