How specific is Geneva Convention?

I've been asked twice recently during radio appearances, "How specific is Geneva Convention with regards to torture?" The insinuation is that it is vague and allows the use of waterboarding.

Here's what it says:
Geneva Convention relative to the Treatment of Prisoners of War
Article 3

To this end the following acts are and shall remain prohibited at any time and in any place whatsoever with respect to the above-mentioned persons:

(a) Violence to life and person, in particular murder of all kinds, mutilation, cruel treatment and torture;

(b) Taking of hostages;

(c) Outrages upon personal dignity, in particular, humiliating and degrading treatment;

(d) The passing of sentences and the carrying out of executions without previous judgment pronounced by a regularly constituted court affording all the judicial guarantees which are recognized as indispensable by civilized peoples.

In addition here the language from the Army Field Manual 2-22.3 Human Intelligence Collector Operations:

All captured or detained personnel, regardless of status, shall be treated humanely, and in accordance with the Detainee Treatment Act of 2005 and DOD Directive 2310.1E, “Department of Defense Detainee Program”, and no person in the custody or under the control of DOD, regardless of nationality or physical location, shall be subject to torture or cruel, inhuman,or degrading treatment or punishment, in accordance with and as defined in US law.

We can argue over semantics, but I know what this means. It is embedded in me as an American and as a member of the Armed Forces. If it's un-American, it's wrong. To me, it doesn't matter what agency you work for -- if you are an American, then you should adhere to American principles.

The Campaign to Ban Torture, whose endorsers include former Secretaries of State, Secretaries of Defense, Retired Four Star Generals, and many others, proposes The Golden Rule:

We will not authorize or use any methods of interrogation that we would not find acceptable if used against Americans, be they civilians or soldiers.

We will win this war by being smarter, not harsher.