Customary International Law in Green's Opinion

I can't restrain myself from another post on Judge Green's opinion in the Guantanamo Bay cases.

On p. 74, Green rules:

Finally, having found that all detainees possess Fifth Amendment due process rights and that some detainees possibly possess rights under the Geneva Conventions, it is unnecessary to look to customary international law to resolve the petitioner's claims. See The Paquette Habana, 175 U.S. 677, 699 (1900) ("where there is no treaty and no controlling executive or legislative act or judicial decision, resort must be had to the customs and usages of civilized nations").

The dismissal of the customary international law (CIL) claims based on these grounds seems rather suspect. For one, the presence of some rights (Fifth Amendment / Geneva Convention) does not exclude the possession of others under CIL. Also, this calculation ignores the fact that Green excluded non-Afghan fighters from the GC claims, which means that there is an entire pool of non-Afghans detained in Guantanamo with (under Green's ruling) no legal structure determining their fate. This seems to be the prototypical circumstance where CIL was envisioned to "fill the cracks" of the treaty-based legal scheme.