The Supreme Court killed a small forest yesterday with the 185 pages of conflicting opinions it issued yesterday in Hamdan v. Rumsfeld, but it all boils down to only two points. First, the courts are ill equipped to deal with the legal complexities raised by the war on terror. And second, Congress can no longer avoid doing something about it. Although the ruling is a defeat for President Bush, it’s certainly not a victory for his opponents.

Salim Ahmed Hamdan, a citizen of Yemen, was captured in Afghanistan in November 2001, having spent the previous five years serving al Qaeda in various ways, including as Osama bin Laden’s driver. Shipped to Guantanamo in June 2002, he was eventually hauled before a military commission established by Mr. Bush to try suspected terrorists. The main charge against him was conspiracy. By a 5-3 vote, the court has now ruled that Congress has not authorized the president to set up this sort of commission, which is neither civilian court nor traditional court martial. Chief Justice Roberts did not participate in the case because he had already ruled on it – in the president’s favor – when he was riding the circuit in the District of Columbia.

The Hamdan Five concluded that the structure of the commissions, which deny defendants access to some classified evidence against them, was illegal under existing statutes and the Geneva Convention. Justices Stevens, Souter, Ginsburg, and Breyer also held that conspiracy is not a legitimate charge for a commission to consider under traditional military law; that finding would have become the law of the land if Justice Sandra Day Kennedy had signed on. Instead, he decided the conspiracy question wasn’t germane in this case, nonetheless leaving the door open that he could change his mind in the future.

The biggest problem is that the court’s normal way of deciding these cases, by investigating precedents and trying to extract conclusions from those, didn’t leave room to address the novel nature of the current war, in which the combatants aren’t fighting for a country and the struggle might necessitate new rules of evidence. The plurality didn’t seem to realize that, unlike in previous wars, conspiracy is the primary occupation of the combatants in this one. Which is precisely why the courts are the wrong venue to settle this kind of dispute.

Justice Thomas, joined by Justices Scalia and Alito, recognized the bramble into which this opinion stumbles. Justice Thomas described the court’s “evident belief that it is qualified to pass on the ‘military necessity’ of the Commander in Chief’s decision to employ a particular form of force against our enemies” as “antithetical to our constitutional structure.” The executive, as the Founders recognized, is capable of acting more swiftly and decisively and has more information available to it than the judiciary. Thus, the president is better suited than judges to adapt to a new kind of war. Instead, the court has taken an action that might, in the words of Justice Thomas, “sorely hamper the President’s ability to confront and defeat a new and deadly enemy.”

At least the court has left a door open to congressional action. “Nothing prevents the President from returning to Congress to seek the authority he believes necessary” to try terror suspects, Justice Breyer wrote in a concurring opinion. That could be a blessing in disguise for Mr. Bush. Many senators and representatives have been more than happy to criticize the way the president has dealt with Mr. Hamdan and other suspected terrorists. Senator Kennedy was quick to praise the court for repudiating “the Bush Administration’s lawless behavior at Guantanamo.” Now the Congress has little choice but to go on the record saying what it would do.

Well, the country awaits the solons. The biggest irony of the ruling, meantime, is that the high court leaves terrorists like Mr. Hamdan in custody. Human rights groupies complained loudly about the commissions the court has struck down. Yet the alternative to a commission that can weigh facts and mete out sentences is indefinite detention with no trial and no appeal. Mr. Bush, and all future presidents, lost out in this ruling curtailing executive power. But it is a pyrrhic victory for his opponents, who must now go on the record explaining exactly what they think we should do with suspected terrorists while the suspects languish in jail with no recourse.