WASHINGTON — 1861. 1941. 2001. Our big wars — and the war on terror ranks with the big ones — have a way of starting on the first year of a decade. Supreme Courts, which historically have been loath to intervene against presidential war powers in the midst of conflict, have tended to give the president until mid-decade to do what he wishes to the Constitution in order to win the war.

During the Civil War, Lincoln suspended the writ of habeas corpus — trashing the Bill of Rights or exercising necessary emergency executive power, depending on your point of view. But he got the whole troublesome business done by 1865 and the Supreme Court stayed away.

During World War II, FDR interned Japanese-Americans. He, too, was left unmolested by the court. But Roosevelt also got his war wrapped up by 1945. Had the current war on terror followed course and ended in 2005, the sensational just-decided Hamdan case concerning military tribunals for Guantanamo prisoners would have either been rendered moot or drawn a yawn.

But, of course, the war on terror is different. The enemy is shadowy, scattered and therefore more likely to survive and keep the war going for years. What the Supreme Court essentially did in Hamdan was to say to the president: Time's up. We gave you the customary half-decade of emergency powers, but that's as far as we go. From now on, the emergency is over, at least judicially, and you're going to have to operate by peacetime rules.

Or as Justice Anthony Kennedy, the new Sandra Day O'Connor, put it, Guantanamo (and by extension, war-on-terror) jurisprudence must henceforth be governed by "the customary operation of the executive and legislative branches." This case may be "of extraordinary importance," but it is to be "resolved by ordinary rules."

All rise: The Supreme Court has decreed a return to normality. A lovely idea, except that al-Qaida has other ideas. The war does go on. One can sympathize with the court's desire for a Harding-like restoration to normalcy. But the robed eminences are premature. And even if they weren't, they really didn't have to issue a ruling this bad.

They declared illegal Bush's military tribunals for the likes of Salim Ahmed Hamdan, Osama bin Laden's driver and bodyguard. First, because they were not established in accordance with congressional authority. And second, because they violated the Geneva Conventions.

The first rationale is an odd but fixable misreading of congressional intent. The second is a grotesque and unfixable misreading of the Geneva Conventions.