T he new John Roberts Supreme Court is only one term old, and already we’re all wrong about it.

Liberals had feared, and conservatives had feted, the end of judicial review as we know it, at least until last week’s blockbuster ruling in Hamdan vs. Rumsfeld proved that bit of conventional wisdom wrong practically before it had become conventional. Predictions of a new era of hands-off judicial minimalism may have been premature.

Yes, we are seeing the expected shift to the political right with the replacement of moderate Justice Sandra Day O’Connor by conservative Justice Samuel Alito. But, more significant, the role of swing justice has itself swung from O’Connor to Justice Anthony Kennedy. On all the most divisive issues, today’s court is now a Supreme Court of One.

Yes, Kennedy, 69 and on the court for 18 years, has inherited the power to decide crucial cases, and this term he showed us what that might mean.

In Hamdan, he joined with the court’s left wing to invalidate the military tribunals President Bush had concocted for the detainees at Guantanamo Bay, Cuba. And the majority opinion he joined, written by Justice John Paul Stevens, was neither minimalist nor mild: “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.”

But more crucial, Kennedy has appropriated O’Connor’s trick of writing an opinion or a concurrence that goes on to become the law of the land. O’Connor was famous (and not always in a good way) for signing onto an opinion, but on narrower grounds than the four other justices in the majority. The trick is that the justice who decides the case most narrowly speaks for the whole court. And that’s how O’Connor imprinted her views on an awful lot of jurisprudence.

But unlike O’Connor, who invariably pooh-poohed her pivotal role on the court by saying she simply had one vote like every other justice, Kennedy is said to relish it. In his controversial book “Closed Chambers,” Edward Lazarus, a former clerk for the late Justice Harry A. Blackmun, claimed that Kennedy deliberately stakes out positions that would make him a “necessary but distinctive fifth vote for a majority.”

The fact that Kennedy is not moored to any one ideology or interpretive theory has led him to some spectacular defections from the court’s conservatives – to the lasting fury of the right. It was Kennedy, after all, who allied with O’Connor and Justice David H. Souter to preserve the core holding of Roe vs. Wade in 1992, and it was Kennedy who wrote the court’s broadest defense for decriminalizing gay sodomy.

Kennedy also voted with the court’s liberals to strike down the death penalty for juveniles and the mentally disabled, and he wrote a crucial opinion prohibiting sectarian prayer at a public-school graduation.

Kennedy is rumored to be easily influenced by his colleagues, the media and his affection for all things foreign, making his critics even more nervous. It sometimes makes his fans even more so. Adam Cohen, of The New York Times, recently wrote of Kennedy that, at the very least, “there is something refreshing about a justice who genuinely seems to have an open mind.”

For years, the law clerks’ “tug of war for Kennedy’s mind” that Lazarus described has been the stuff of insider speculation. Now that Kennedy is the court’s lone swing vote, that spectacle has become increasingly public.

From Focus on the Family founder James Dobson, who famously called Kennedy “the most dangerous man in America,” to advocates at the court, who more and more frequently respond to the justice during oral arguments as though they were addressing themselves to the burning bush, trying to influence Kennedy has become something of an Olympic event. The hottest game in Supreme Court brief-writing is to quote Kennedy gratuitously and often. In other words, flattering Kennedy has become something of an art.

The other justices are playing the quote-Kennedy game, too, presumably in hopes of wooing him to their side. Read, for example, the opinion and dissent in Rapanos et al. vs. United States, the term’s main environmental case. Each side made sure to send a love note to Kennedy.

The justices may also be cozying up to Kennedy in other ways: He won himself some sweet writing assignments this term. Some court-watchers have suggested that the bizarre trio of Kennedy, Roberts and Stevens, who jointly issued a strange concurring opinion in the Jose Padilla case last April, was yet another effort by the court’s right- and left-wing leaders to show Kennedy a little more love.

Roberts is a savvy insider who knows that, over the years, the abuse heaped on the court’s moderates from the right has pushed them into the arms of the court’s liberals. So Kennedy is now being love-bombed.

And what is the crucial swing voter doing with his newfound superpowers? While it’s still too early to predict, the invaluable annual end-of-term tally done by SCOTUSblog shows that Kennedy voted with the majority 84 percent of the time. In the 11 cases decided 5 to 4 this term, Kennedy was in the majority 75 percent of the time. He wrote the second-highest number of opinions, the most concurrences and only two dissents.

But again, that’s also only half the story. The other half is how Kennedy used that vote to shape the law.

It was Kennedy who provided the fifth vote in Hudson vs. Michigan, an amazing criminal law case, in which he voted with the court’s four reliably conservative jurists – Alito, Roberts, Antonin Scalia and Clarence Thomas – to hold that the remedy for police violations of the centuries-old “knock and announce” rule, required whenever the cops serve a warrant, was, in effect, nothing.

But while Scalia’s majority opinion showed a readiness to end the practice of throwing out evidence obtained illegally, Kennedy’s moderating fifth vote put on the brakes by insisting that the general rule of excluding evidence gained illegally was not in jeopardy. Future challenges to the exclusionary rule may hereafter be posed to the Kennedy Court of One.

Kennedy also provided the key fifth vote in Rapanos. The case tested the authority of the Army Corps of Engineers to enforce the Clean Water Act, and the four conservative justices would have dramatically curtailed the powers of the Corps. It was Kennedy – again writing separately – who refused to go as far as Scalia urged. And it was Kennedy whose opinion in Rapanos will thus become the standard for the Corps as it fashions future policy.

Looking forward to next year’s big greenhouse gases case, which explores whether the Environmental Protection Agency has an obligation to regulate carbon dioxide, a lawyer for the Sierra Club has already suggested that “Rapanos means … we will write our brief for Anthony Kennedy and maybe a little bit for Roberts.”

Kennedy’s was the moderating fifth voice again in the cacophony of the Texas redistricting case, where he sided with the court’s conservatives to defeat the claim that then-Rep. Tom DeLay’s mid-decade redistricting was unconstitutional. Nevertheless, he joined with the liberals to find that a new congressional district violated the rights of Hispanic voters. Once again, a Court of One.

And Hamdan, probably the most consequential separation-of-powers case in recent memory, also pivoted on Kennedy’s vote. He sided with the liberals, while refusing to go as far as they would have led him.

What does all this nipping and tucking, shucking and jiving mean for Kennedy and the court? He clearly plans to fill the shoes recently vacated by O’Connor; shoes she, in turn, inherited from Justice Lewis Powell.

They each played the role of moderating a polarized court; building bridges, navigating toward the center – a center where most of the nation was most comfortable. Each took abuse for that when they sat on the court. Each was largely celebrated for it when they retired.

Kennedy, too, appears poised to hold that center together. Indeed more often than not, he seems to be leaving his options open, laying the groundwork for revisiting these issues more fully in the future, as he becomes more comfortable in this role.

Much of the soaring rhetoric for which Kennedy was famed in previous years – opinions that brimmed with “the ineffable glory of unflinching human dignity” and such – seems to have been toned down of late. But then, perhaps Kennedy doesn’t need to write about the ineffable glory of anything anymore. He can just sit back and bask in it instead.