We already knew this... + Constitutional comment

From INQUIRY INTO THE TREATMENT OF DETAINEES IN U.S. CUSTODY:

On February 7,2002, President Bush signed a memorandum stating that the Third Geneva Convention did not apply to the conflict with al Qaeda and concluding that Taliban detainees were not entitled to prisoner of war status or the legal protections afforded by the Third Geneva Convention.
[Executive Summary, xiii]

I note that:

"The Congress shall have power...
... To define and punish piracies and felonies committed on the high seas, and offenses against the law of nations;
...
... To declare war, grant letters of marque and reprisal, and make rules concerning captures on land and water;
...
... To make rules for the government and regulation of the land and naval forces;..."
[Article I, Section 8, U.S. Constitution; emphasis added]

All of which is to say: W had not the Constitutional competence to declare that al Qaeda & Taliban detainees were not entitled to Prisoner of War status & the legal protections afforded by the Third Geneva Convention! - This Constitutional competence lay - and lies - solely with Congress!
Under a strict constructionist interpretation of the Constitution (that which was once favored by conservatives!), W's memorandum had no legal force!