This exchange between Solicitor General Verrilli and Justice Kagan towards the end sums up what is at issue here quite clearly:
GENERAL VERRILLI: And I think, if you take a step back, think — ask — think about what they’re asking you to do. They are asking you to invalidate a vitally important national security statute based not on a concrete application —
JUSTICE KAGAN: No, General Verrilli, this is not about the merits of the statute. They might have no claim on the merits at all, and so there would be no question of invalidation. The question is only: Can they make their argument to a court?
Even if the plaintiffs have standing, what would any court do with this case?
Likewise, the Guantanamo cases were not about the noble history of the writ of habeas corpus or ensuring the detainees were freed. And I think even with Boumedienne four years in the past, Gitmo is still open for business under new ownership.
I still have to chuckle that President Obama is the President defending these types of programs in the Supreme Court. Fortunately (or unfortunately?), an Obama appointee, Justice Kagan, is not so persuaded.