Got an honest-to-goodness landmark decision coming down within the next few hours. Will it be military tribunals or federal district court for the Gitmo gang? SCOTUSblog holds a finger to the wind and says a storm’s a-comin’.

If they’re right, it’ll probably shake out 5-3, with Scalia, Thomas, and Alito in dissent. (Roberts took part in the case at the circuit-court level so he’s recused himself.) As the senior member of the majority, Stevens gets to assign the opinion; this one’s big enough that he’ll probably take it himself, but there’s a small chance he’ll hand it off to Kennedy, as he’s done with some of the gay-rights cases over the past ten years. His strategy is to tie Kennedy, the swing vote, to the decision by making him put his name on it. It makes it harder for him to change his mind later when new cases in this line come up.

Silver lining? Is this Stevens’s last hurrah? He’s 86 and looking at two and a half years before a Democrat can appoint his successor. Why not go out with a bang with Hamdan? It’lll cement his “legacy” among the left, like Elway quitting after winning the Super Bowl. Plus, it’s the last day of the term, a time when Justices often announce their retirements. (O’Connor waited a week last year before quitting on July 1.)

Bonus silver lining! Imagine the looks on nutroots faces were Hamdan to come out in their favor — followed a few hours later by news that Stevens is riding off into the sunset. That would almost make it worth losing. “Shane! Come back, Shane!

Questioning the timing: Would the midterm elections factor into his retirement decision? If he quits over the summer, the Republicans would want to hold hearings and confirm his successor before the new, possibly Democratic Senate is seated in January. The current Democratic leadership naturally would want to delay and obstruct until after the election. The vacancy would also become a huge election issue, which I doubt Stevens wants to see happen. Figure if he’s going to quit, then, it’ll be after the fall term, not this one.

If Bush does have to deal with a Democratic Senate (or at least a more Democratic Senate, which is almost certain), would he try to replace Stevens with Luttig? Luttig, remember, is a hardline conservative who fell out with the administration over … detainment of enemy combatants. That would be a point in his favor before the Democrats, as would the symmetry of him replacing the author of the Hamdan opinion on the Court. And Bush could point to the appointment as proof that he respects judges who disagree with him.

Or, maybe Stevens isn’t retiring and our side won in Hamdan. Anyway, speculation is fun!

Update: The boss is getting bad vibes, too.

Update: Just across at Fox and CNN: Court rules Bush “overstepped his authority.” 5-3 decision, written by Stevens, Kennedy the defector from the conservative side. As expected. Holding: the Geneva Conventions must apply to the proceedings.

Update: Andy McCarthy predicted it, and says it comes down to this:

[I]t seems like there’s a prevailing view that if — as expected — the decision comes out in favor of Hamdan, the theory will be that al Qaeda does have Geneva Convention protections.

Make no mistake: if this happens, the Supreme Court will have dictated that we now have a treaty with al Qaeda — which no President, no Senate, and no vote of the American people would ever countenance. (Compare this.) The Constitution consigns treaty-making to the political branches, not the courts, but a conclusion that Geneva protects Hamdan (and, by extension, his fellow savages) would ominously mean that the courts, under the conveniently malleable guise of “customary international law” can rewrite treaties to mean whatever they like them to mean.

Update: What to make of this? From SCOTUSblog:

The Court expressly declared that it was not questioning the government’s power to hold Salim Ahmed Hamdan “for the duration of active hostilities” to prevent harm to innocent civilians. But, it said, “in undertaking to try Hamdan and subject him to criminal punishment, the Executive is bound to comply with the Rule of Law that prevails in this jurisdiction.”

So if they try him, they have to take him to federal court — but they don’t have to try him? What?

Update: Alito, Scalia, and Thomas all wrote separate dissents, which suggests some pretty serious outrage. I’ll have the links once the opinions are up.

Update: According to SCOTUSblog, Ginsburg, Kennedy, and Souter joined Breyer in saying:

The Court’s conclusion … “ultimately rests upon a single ground: Congress has not issued the Executive a ‘blank check.’… Indeed, Congress has denied the President the legislative authority to create military commissions of the kind at issue here. Nothing prevents the President from returning to Congress to seek the authority he believes necessary.

They can try them in military tribunals, in other words. They just can’t do it on the say-so of the president alone.

Update: Marty Lederman of SCOTUSblog thinks the decision is huge — and not for anything it has to say about tribunals.

The Court appears to have held that Common Article 3 of Geneva aplies to the conflict against Al Qaeda. That is the HUGE part of today’s ruling. The commissions are the least of it. This basically resolves the debate about interrogation techniques, because Common Article 3 provides that detained persons “shall in all circumstances be treated humanely,” and that “[t]o this end,” certain specified acts “are and shall remain prohibited at any time and in any place whatsoever”—including “cruel treatment and torture,” and “outrages upon personal dignity, in particular humiliating and degrading treatment.” This standard, not limited to the restrictions of the due process clause, is much more restrictive than even the McCain Amendment.

Is Lederman overstating things? Lyle Denniston at SCOTUSblog points out that “Kennedy’s opinion did not support all of Stevens’ discussion of the Geneva Convention, but he did find that the commissions were not authorized by military law or that Convention.” Any part of the majority opinion that Kennedy didn’t sign on to has no precedential value.

Update: The opinions have been posted. I’m off to skim.

Update: Bush has a press conference with Koizumi coming up at 11:30. He might deflect questions about the ruling on grounds that they’re still looking at the decision. If anything interesting is said, I’ll have video.

Update: The ACLU rejoices.

Update: Think Progress thinks the decision spells doom for the warrantless wiretap program. Interesting point.

Update: Video of Bush’s press conference is here. The Times reports that Justice Thomas was sufficiently piqued that he read his dissent from the bench — the first time he’s done so in fifteen years on the Court.