The politics or policies of the US government are that detainees are to be treated according to the Geneva Convention.
In reality, they're not doing that, hence the rumblings from the UN and allies of the US.
The detainees at Guantanamo Bay for example are being held there in contravention of International Law but treated (allegedly) according to International Law....which is a bit of a joke as they have no access to lawyers as well as a whole host of other things.