Various excerpts (citations omitted) from Justice Scalia’s dissent (joined by the Chief Justice and Justices Thomas and Alito):
Today, for the first time in our Nation's history, the Court confers a constitutional right to habeas corpus on alien enemies detained abroad by our military forces in the course of an ongoing war…. The writ of habeas corpus does not, and never has, run in favor of aliens abroad; the Suspension Clause thus has no application, and the Court's intervention in this military matter is entirely ultra vires.
The game of bait-and-switch that today's opinion plays upon the Nation's Commander in Chief will make the war harder on us. It will almost certainly cause more Americans to be killed. That consequence would be tolerable if necessary to preserve a time-honored legal principle vital to our constitutional Republic. But it is this Court's blatant abandonment of such a principle that produces the decision today. The President relied on our settled precedent in Johnson v. Eisentrager (1950), when he established the prison at Guantanamo Bay for enemy aliens.
[I]n response [to the Court’s 2006 ruling in Hamdan v. Rumsfeld], Congress, at the President's request, quickly enacted the Military Commissions Act, emphatically reasserting that it did not want these prisoners filing habeas petitions. It is therefore clear that Congress and the Executive—both political branches—have determined that limiting the role of civilian courts in adjudicating whether prisoners captured abroad are properly detained is important to success in the war that some 190,000 of our men and women are now fighting…. What competence does the Court have to second-guess the judgment of Congress and the President on such a point? None whatever. But the Court blunders in nonetheless. Henceforth, as today's opinion makes unnervingly clear, how to handle enemy prisoners in this war will ultimately lie with the branch that knows least about the national security concerns that the subject entails.
What drives today's decision is neither the meaning of the Suspension Clause, nor the principles of our precedents, but rather an inflated notion of judicial supremacy. The Court says that if the extraterritorial applicability of the Suspension Clause turned on formal notions of sovereignty, "it would be possible for the political branches to govern without legal constraint" in areas beyond the sovereign territory of the United States. That cannot be, the Court says, because it is the duty of this Court to say what the law is. It would be difficult to imagine a more question-begging analysis.… Our power "to say what the law is" is circumscribed by the limits of our statutorily and constitutionally conferred jurisdiction. And that is precisely the question in these cases: whether the Constitution confers habeas jurisdiction on federal courts to decide petitioners' claims. It is both irrational and arrogant to say that the answer must be yes, because otherwise we would not be supreme.
Putting aside the conclusive precedent of Eisentrager, it is clear that the original understanding of the Suspension Clause was that habeas corpus was not available to aliens abroad, as Judge Randolph's thorough opinion for the court below detailed.… It is entirely clear that, at English common law, the writ of habeas corpus did not extend beyond the sovereign territory of the Crown.
Today the Court warps our Constitution in a way that goes beyond the narrow issue of the reach of the Suspension Clause, invoking judicially brainstormed separation-of-powers principles to establish a manipulable "functional" test for the extraterritorial reach of habeas corpus (and, no doubt, for the extraterritorial reach of other constitutional protections as well). It blatantly misdescribes important precedents, most conspicuously Justice Jackson's opinion for the Court in Johnson v. Eisentrager. It breaks a chain of precedent as old as the common law that prohibits judicial inquiry into detentions of aliens abroad absent statutory authorization. And, most tragically, it sets our military commanders the impossible task of proving to a civilian court, under whatever standards this Court devises in the future, that evidence supports the confinement of each and every enemy prisoner. The Nation will live to regret what the Court has done today.