"Is there no way to bring the War on Terror fully under legal, constitutional, even political restraints?"
Is this a rhetorical question? I'll assume it isn't. Here's the answer: No, there is no way to bring the War on Terror fully under legal, constitutional, even political restraints. That is because from its inception the "War" on Terror was *designed* to act outside of legal, constitutional, and political constraints. That's the point--to wipe out legal, constitutional, and political constraints to state power. I'm not sure I have to explain further, as this article itself provides sufficient evidence.
If one was really serious about putting the "War" on Terror under the rule of law, there is an option available immediately: Indict Woo, Holder, Bush, Cheney, etc. (Obama would have to be impeached). This is of course unsayable and all but unthinkable in the US, but it's not as if other countries haven't noticed:
March 29, 2012 Poland indicts former spymaster over CIA renditions
http://euobserver.com/22/115745
What this suggests is that constitutionalism and the rule of law can be taken seriously in Poland. In the US, "constitutionalism" and "the rule of law" appear to have been reduced to meaningless slogans, even under the already limited standards of a capitalist-controlled republic.