Rights for Detainees

The debate of late about detainees' fate at Gitmo has provoked a spate of boilerplate from the administration. The official line appears to be: "We are sticking by our guns."
The prevailing climate at the White House, at least as it is transmitted through the media -when is the last time I was at the White House to see how things actually are run?- is to agree with decisions by lawmakers, then to amend those decisions with an executive spin. For instance, pertaining to the recent Supreme Court decision that detainees held at Guantanamo Bay have rights consistent with international standards for civilisation, as represented by Common Article 3 in the Geneva Conventions, a statement went out that the administration stood by the Court's ruling. That was two days ago.
Today administration lawyers are arguing that the "best solution" for Congress moving forward will be to adopt the military tribunals that the president has been pushing now for four years. In other words, Congress is free to abide by the Court's ruling... so long as it is in line with the design already laid down by the executive.
This kind of top-down thinking does not appear to be in line with democratic values, at least so far as those established by the US constitution. The impression instead is of a ruling cabinet that dictates national policy and then waits for legal aspects to fall in place.
Is this not operating outside the law? I don't mean to ask rhetorically, but literally: is the executive making up a new form of constitional rule, one that falls outside the parametres of the constitution itself?
As you might imagine, I am following developments in this case very closely... desperately, one might say. After all, I love my country and do not wish to see it overrun by Machiavellian Mayberrianism... or anything resembling it.