Which court?

The Supreme Court term beginning today offers Chief Justice John G. Roberts Jr. and his colleagues a fresh opportunity to realize Roberts’ vision of a court that speaks with a single voice and moves cautiously in upending established law. They should seize it.

Both consensus and caution were in shamefully short supply in the court’s 2006-07 term, and so was civility. Twenty-four cases were decided by 5-4 majorities. Liberals quarreled with conservatives. Conservatives quarreled among themselves. Roberts himself -- an exponent of judicial “modesty” -- joined in an immodest evisceration of past decisions on race, abortion and the separation of church and state.

It was always unrealistic to expect that the justices would get along even when they deeply disagreed. Still, in the 2005-06 term -- the first under Roberts -- the court generally kept the hair-splitting under control, in part because it was a time of transition, with Justice Samuel A. Alito Jr. replacing Justice Sandra Day O’Connor midterm.

Some of the upheavals of the 2006-07 term -- including an unjustified U-turn on so-called partial-birth abortions -- can be explained by O’Connor’s departure. But another factor was the inability or unwillingness of the chief justice to make good on his soothing words to the Senate Judiciary Committee about the importance of continuity and consensus. Roberts had told the panel that overturning a Supreme Court precedent causes a “jolt to the legal system.” But last term he joined conservative colleagues in administering unnecessary shock therapy to important precedents. Is there any reason to expect that the 2007-08 term will be different?

The justices themselves -- liberal and conservative -- may be interested in lowering the decibel level. Moreover, none of the cases the court has agreed to review are as divisive and ideologically charged as the abortion or race cases of last term. But one case will test the commitment of the chief justice and his colleagues to both consensus and continuity.

After initially refusing to do so, the court has agreed to hear a challenge by two inmates at Guantanamo Bay to a law depriving them of the right to challenge their confinement by seeking a writ of habeas corpus. In 2004 and 2006, the court ruled that inmates could seek habeas relief under a federal statute. But Congress obliged the Bush administration by excluding such protection from the Military Commissions Act of 2006. Efforts to undo that unjust exclusion have failed.

Now the court must decide whether the Constitution guarantees habeas protection to inmates at Guantanamo, a de facto U.S. territory, and, if so, why similar relief wouldn’t be available to alleged terrorists held overseas. Drawing such lines in a way that will win public and congressional respect will require more collegiality than the Roberts court displayed in its sophomore term.