I have not yet had a chance to fully study the Court's opinion in Boumediene v. Bush. But I will note one very important aspect of this case that differs from the Court's previous war on terror decisions rebuking the Bush administration. In earlier cases such as Rasul v. Bush, Hamdi v. Rumsfeld, and Hamdan v. Rumsfeld, the Court invalidated unilateral actions taken the by the executive, repudiating the Bush Administration's ultra-expansive interpretation of wartime executive power. However, Hamdan specifically left open the possibility that the administration's Guantanamo policies might be constitutional if authorized by congressional legislation. The Republican Congress (for the most part) provided that authorization in the Military Commissions Act of 2006.

In Boumediene, the Court challenges congressional power as well as the executive. It strikes down as unconstitutional several provisions of the Detainee Treatment Act of 2005 and the MCA. This is a nearly unprecedented situation where the Court rejected an important assertion of wartime power backed by both of the other branches of government. To my knowledge, virtually every previous case in which the Court ruled an important wartime policy unconstitutional was one where the policy in question was adopted by the executive acting alone.

As a political matter, the majority justices might might well have reasoned that they could avoid a dangerous interbranch confrontation because the Republican Congress which enacted the DTA and MCA is now gone, and the Bush Administration has only a few months remaining. But even a Democratic administration and Congress might be reluctant to give terrorist detainees as much protection as Boumediene requires.

The fact that the decision challenges congressional power as well as executive power doesn't mean that it is necessarily wrong. On that question, I am divided in my own mind. The difficult question is whether habeas corpus applies to enemy combatants seized in operations abroad (I don't doubt that the Bush Administration was wrong to assert that it doesn't apply to US citizens accused of terrorist acts and captured in the US).

Importantly, the Court does leave Congress a way out. If it wants to, Congress could still strip detainees of the protection they get under Boumediene by enacting a statute suspending the writ of habeas corpus under the Suspension Clause. With a Democratic Congress, I suspect that we might get a new detainee law that suspends the writ for certain categories of terror detainees, but also perhaps gives them more procedural rights than they got under the Republican-enacted MCA. For a variety of reasons, I doubt that the Democrats will be willing to take the risk of allowing the detainees to retain full habeas rights. If they don't act and a terrorist released as a result of a habeas petition commits some atrocity, the Dems will take a predictable political hit. Especially if Obama wins the presidential election, expect the Democrats to enact some sort of partial suspension of habeas corpus, combined with new, but limited statutory procedural rights for detainees. At least that is my tentative prediction.

UPDATE: Some commenters cite Ex Parte Milligan as an example of a case where the Court invalidated a joint congressional-executive wartime policy. In a narrow technical sense, they have a point. However, it is important to recognize that Milligan was decided only after the war in question (the Civil War) was over. The Court would have been much more reluctant to take on both of the other branches if the war had still been ongoing (as of course it still is in the Boumediene case).

UPDATE #2: As Marty Lederman points out in an e-mail to me, the Milligan decision actually held that the president lacked congressional authorization for his actions in so far as the Habeas Corpus Act of 1863 forbade him to subject civilians to military jurisdiction in states where the civilian courts continued to operate. The Court also ruled that, in some situations, even Congress would lack the power to subject civilians to military trials; but it emphasized that Congress had not taken any such action in the case before it. Be that as it may, it is significant that even in Milligan, the Court did not repudiate both of the other branches of the federal government head on, in the way it has now done in Boumediene.