Akuma, perhaps I'm wrong but I was under the impression that the eighth amendment, and the constitution in general, doesn't apply to those who are not US citizens. Otherwise they would be vulnerable to prosecution for treason under Article 3 Section 3. I could be wrong but I believe it is Article 3 Section 2 specifically which enumerates the parties to which the power of the judicial branch apply.
Either way the point is made moot because we are not discussing a punishment. We are discussing interrogation methodology. Punishment comes later.
For good measure, some examples of what they meant by cruel and unusual punishment as listed by the Supreme Court: drawing and quartering, public dissecting, burning alive, or disemboweling.
None of those are even remotely comparable to waterboarding.








