Justice Stevens makes some good points in Rasul v. Bush

(from The Nine, by Jeffrey Toobin)

 The Bush legal team, led by Ted Olson, the solicitor general, brought the same moral certainty to the Supreme Court that the Republican political operation put forth to voters. The issues were straightforward, the choices binary: the United States or the terrorists, right or wrong. Standing up to argue in Rasul, Olson laid the same kind of choice before the Court. "Mr. Chief Justice, and may it please the Court: The United States is at war," Olson began with heavy portent. "It is in that context that petitioners ask this Court to assert jurisdiction that is not authorized by Congress, does not arise from the Constitution, has never been exercised by this Court."

But if this kind of talk was intended to intimidate the justices, as it cowed so many others, the tactic did not work. Indeed, it backfired. "Mr. Olson, supposing the war has ended," Stevens jumped in, "could you continue to detain these people on Guantanamo?" Of course we could, Olson said. In other words, the military could detain Rasul and the others whether or not there was a war.

"The existence of the war is really irrelevant to the legal issue," Stevens said.

"It is not irrelevant because it is in this context that that question is raised," Olson replied weakly.

"But your position does not depend on the existence of a war," Stevens insisted, and Olson had to concede it did not. So in just the first moments of the argument, Stevens had shown that the Bush administration was claiming not some temporary accommodation but rather a permanent expansion of its power for all time, in war or peace. And Stevens was showing further that Olson's rhetorical flourish--"The United States is at war"-- was nothing more than posturing. (p. 231)

...

So, it turned out, was the preposterousness of the administration's key argument in Rasul. Olson had maintained that the navy base in Guantanamo was really Cuban soil and to allow a lawsuit there was inviting litigation on a foreign battlefield. But as Stevens put it in his opinion, "By the express terms of its agreements with Cuba, the United States exercises "complete jurisdiction and control' over the Guantanamo Bay Naval Base and may continue to exercise such control permanently if it so chooses." The entire reason that the military took the detainees to such a remote outpost was because the base offered total freedom from outside interference. Allowing lawyers to visit prisoners in Guantanamo and letting them conduct litigation offered no risk at all of escape or disruption--something that could not be said for many prisons within the United States. (p. 235)