Supreme Court Justices are remembered for their opinions, but they are revealed by their questions. For many years, Sandra Day O’Connor chose to open the questioning in most cases, and thus show the lawyers—and her colleagues—which way she, as the Court’s swing vote, was leaning. Today, Antonin Scalia often jumps in first, signalling the intentions of the Court’s ascendant conservative wing, and sometimes Chief Justice John G. Roberts, Jr., makes his views, which are usually aligned with Scalia’s, equally clear. New Justices tend to defer to their senior colleagues, but Sonia Sotomayor, in her first year on the Court, has displayed little reluctance to test lawyers on the facts and the procedural posture of their cases; these kinds of questions had generally been the province of Ruth Bader Ginsburg, who, at times, has not seemed entirely pleased by the newcomer’s vigor. Samuel A. Alito, Jr., often says little; Clarence Thomas never says anything. (Thomas has not asked a question at an oral argument since 2006.)

Stevens, asked if he regrets any recent Court decisions, says, “There are a lot I’m very unhappy with.” Photograph by Steve Pyke

John Paul Stevens, who will celebrate his ninetieth birthday on April 20th, generally bides his time. Stevens is the Court’s senior Justice, in every respect. He is thirteen years older than his closest colleague in age (Ginsburg) and has served eleven years longer than the next most experienced (Scalia). Appointed by President Gerald R. Ford, in 1975, Stevens is the fourth-longest-serving Justice in the Court’s history; the record holder is the man Stevens replaced, William O. Douglas, who retired after thirty-six and a half years on the bench. Stevens is a generation or two removed from most of his colleagues; when Roberts served as a law clerk to William H. Rehnquist, Stevens had already been a Justice for five years. He was the last nominee before the Reagan years, when confirmations became contested territory in the culture wars (and he was also, not coincidentally, the last whose confirmation hearings were not broadcast live on television). In some respects, Stevens comes from another world; in a recent opinion, he noted that contemporary views on marijuana laws were “reminiscent of the opinion that supported the nationwide ban on alcohol consumption when I was a student.”

Ever since last fall, when it emerged that Stevens had hired only one law clerk for the next year, instead of his customary four, there has been growing speculation that he will soon retire. Since 1994, Stevens has been the senior Associate Justice and so has been responsible for assigning opinions when the Chief Justice is not in the majority. He has used that power to build coalitions and has become the undisputed leader of the resistance against the conservatives on the Court. “For those fifteen years, John Stevens has essentially served as the Chief Justice of the Liberal Supreme Court,” Walter Dellinger, who was the acting Solicitor General in the Clinton Administration and is a frequent advocate before the Court, says. In Stevens’s absence, leadership of the Court’s liberals would fall, by seniority, to Ginsburg, but she is also elderly and has suffered from a range of health problems. Even if President Obama appointed a like-minded replacement for Stevens, that person, while taking his seat, would not fill his role.

Stevens is an unlikely liberal icon. When he was appointed, he told me recently, he thought of himself as a Republican and always had—“ever since my father voted for Coolidge and Harding.” He declined to say whether he still does. For many decades, there have been moderate Republicans on the Court—John M. Harlan II and Potter Stewart (appointed by Eisenhower), Lewis F. Powell and Harry Blackmun (Nixon), David H. Souter (Bush I). Stevens is the last of them, and his departure will mark a cultural milestone. The moderate-Republican tradition that he came out of “goes way back,” Stevens said. “But things have changed.”

So has Stevens. His positions have evolved on such issues as civil rights and the death penalty, and he has led the Court’s counteroffensive against the Bush Administration’s treatment of the detainees at Guantánamo Bay. And, as Stevens’s profile has risen, and his views have moved left, so, too, has criticism of him from conservatives reached a higher pitch. “From the beginning of his time as a Justice, you could see Stevens’s roots in the New Deal Court and his willingness to justify an expanding welfare state,” Richard Epstein, a libertarian-leaning law professor at New York University, said. “On these issues, he’s been consistent and consistently wrong about everything—and highly influential.”

Still, Stevens’s views suggest a sensibility more than a philosophy. Many great judicial legacies have a deep theoretical foundation—Oliver Wendell Holmes’s skeptical pragmatism, William J. Brennan’s aggressive liberalism, Scalia’s insistent originalism. Stevens’s lack of one raises questions about the durability of his influence on the Court.

But, more than anything, his career shows how the Court has become a partisan battlefield. In that spirit, Roberts last week denounced President Obama’s criticism of the Court in his State of the Union address, saying that the occasion had “degenerated to a political pep rally.” When Stevens leaves, the Supreme Court will be just another place where Democrats and Republicans fight.

Stevens tends to weigh in at oral argument at around the halfway point, and he does something that none of his colleagues do: he asks permission. “May I ask you a question?” or “May I ask you this?” Frequent advocates find this tic amusing and endearing, a little like the bow ties that he always wears. “However Justice Stevens is going to come out on an issue, he is going to do it in a way that is very friendly and avuncular and good-natured,” Paul Clement, who was George W. Bush’s Solicitor General from 2005 to 2008, says. “He’ll say something like ‘This is probably obvious, but I have this one question. Could you help me with this one point?’ An experienced advocate knows that you have to be on your guard, because he’s probably found the one issue that puts your case on the line.” Jeffrey Fisher, who clerked for Stevens in the 1998-99 term and is now a professor at Stanford, says, “The reason he very rarely speaks first is that he really listens to his colleagues and tries to figure out what is on their minds and tries to figure out what the swing votes care about in the case.”

On September 9th last year, Stevens engaged in a classic version of advocacy-by-interrogation during the argument of Citizens United v. Federal Election Commission. The Court was hearing the case before the first Monday in October, the traditional start of its year—an indication of how important some of the Justices thought it was. In 2008, Citizens United, a right-leaning nonprofit organization, had used some corporate contributions, along with money from individuals, to produce and promote a documentary critical of Hillary Clinton. (“She is steeped in controversy, steeped in sleaze,” the narrator says.) The group planned a video-on-demand broadcast on the eve of several Democratic primaries. But the Bipartisan Campaign Reform Act of 2002 (also known as McCain-Feingold, after its two chief sponsors) forbids political advertisements paid for by corporations in the weeks before a primary. Citizens United challenged the law, asserting that its right to freedom of speech was violated.

The Court had first heard arguments in the case in March, 2009, and the questions raised then were mostly narrow ones—whether McCain-Feingold pertained to video-on-demand technology, for example. Months passed without a decision. But, in June, the Court issued an unsigned order asking for the case to be reargued on new terms. Such an order, which requires a majority, had never been issued since Roberts became Chief Justice, in 2005, and only rarely in earlier years. The Court now told the lawyers to address much broader issues about the relationship of corporations to the First Amendment. Specifically, it asked whether two decisions, from 1990 and 2003, which upheld restrictions on corporate speech, should be overturned.

For a century, Congress and the Supreme Court had been restricting the participation of corporations, and individuals, in elections, mostly through limits on campaign contributions. The Court had come to see campaign spending as a form of speech, but one that clearly could be regulated, especially if the speaker was a business. The notion that corporations did not have the same free-speech rights as human beings had been practically a given of constitutional law for decades, and the 1990 and 2003 decisions (both joined by Stevens) reflected that consensus. Now the Court seemed open to what had been radical notions—that corporations had essentially the same rights as individuals, and could spend potentially unlimited amounts of money in elections.

Stevens never uses his questions to filibuster, and his first query was simple. “Does the First Amendment permit any distinction between corporate speakers and individual speakers?” he asked Theodore B. Olson, the lawyer for Citizens United and a Solicitor General in the second Bush Administration.

Olson hedged, saying, “I am not—I’m not aware of a case that just—”

“I am not asking you that,” Stevens persisted. “I meant in your view does it permit that distinction?”

Finally, Olson said, “I would not rule that out, Justice Stevens. I mean, there may be.”

Stevens was trying to alert his colleagues to the extreme shift in the law the case implied. But Roberts, Scalia, Thomas, and Alito had already made plain that they were seeking just such a change. As has often been the case, Stevens’s only hope appeared to be to get the vote of Anthony M. Kennedy, to make a majority with himself, Ginsburg, Stephen G. Breyer, and Sotomayor. (So far, Sotomayor seems to be voting much like Souter, an ally of Stevens, whom she replaced.) When Elena Kagan, the Solicitor General, rose to defend McCain-Feingold, Stevens had his chance.

Stevens asked Kagan if it would be possible for the Court to rule narrowly. There could, for example, be an exception for nonprofits like Citizens United, or for “ads that are financed exclusively by individuals even though they are sponsored by a corporation.” Kagan, grasping the lifeline that Stevens was throwing her, said, “Yes, that’s exactly right.”

“Nobody has explained why that wouldn’t be a proper solution, not nearly as drastic,” Stevens went on. “Why is that not the wisest narrow solution of the problem before us?”

His strategizing was for naught. In a decision announced on January 21st, Kennedy, joined by the four conservatives, wrote a breathtakingly broad opinion, overturning the 1990 decision and much of the 2003 decision, and establishing, for the first time, that corporations have rights to free speech comparable to those of individuals. In the 1990 case, the Court’s majority opinion cited “the corrosive and distorting effects of immense aggregations of wealth that are accumulated with the help of the corporate form and that have little or no correlation to the public’s support for the corporation’s political ideas.” Kennedy’s opinion simply asserted that “independent expenditures, including those made by corporations, do not give rise to corruption or the appearance of corruption.”

Stevens’s ninety-page dissenting opinion in Citizens United (the longest of his career) was joined in full by Ginsburg, Breyer, and Sotomayor, and was a slashing attack on the majority, laden with sarcastic asides. “Under the majority’s view, I suppose it may be a First Amendment problem that corporations are not permitted to vote, given that voting is, among other things, a form of speech,” he wrote.

To make his displeasure clear, Stevens read his dissent from the bench. Justices usually read pared-down versions of published opinions, but Stevens prepared a twenty-minute stem-winder. When the moment came, however, he stumbled frequently, skipped words, and, at times, was hard to understand. (As when he said, “As the corp, court has long resembled . . .”) For the first time in public, Stevens looked his age.

Stevens charged that the way the majority had handled the case was even worse than the legal outcome. “There were principled, narrower paths that a Court that was serious about judicial restraint could have taken,” he wrote. “Essentially, five justices were unhappy with the limited nature of the case before us, so they changed the case to give themselves an opportunity to change the law.” He added, referring to the Court, “The path it has taken to reach its outcome will, I fear, do damage to this institution.” It suggested that, after thirty-five years on the Supreme Court, John Paul Stevens was about to walk away from a place he no longer recognized.

Several weeks later, I sat with Stevens in his sun-streaked chambers at the Court. He had begun his day with a tennis game (singles), then showered and changed into a white dress shirt, suit, and bow tie at the Court. He wears a hearing aid, but walks at an athlete’s loping pace and shakes hands with a punishing grip; he keeps two well-used putters on hand to practice his short game on the office carpet.

For many years, Stevens, who grew up in Chicago, and his wife have divided their time between Washington and Fort Lauderdale, where they own a condominium. In the nineteen-eighties, Court insiders dubbed Stevens the FedEx Justice, because he spent so much time in Florida and corresponded with his chambers by overnight mail. Stevens still flees Washington at every opportunity, especially in the winter (though he now communicates electronically). He deals with his colleagues mostly by memorandum, occasionally by telephone, and rarely in person, except when the Court is in session. His law clerks report that months go by without another Justice visiting his chambers. Under Chief Justice Rehnquist, most of the Justices kept their distance from one another, and this has continued under Roberts, but Stevens in particular is, while cordial, remote.

Yet in person Stevens is as genial as he appears on the bench. He is ever hopeful about his home-town Cubs, and a devoted player, and fan, of golf—“though I have to confess, I miss Tiger.” His financial-disclosure form lists honorary memberships in four country clubs—near Chicago, near Indianapolis, near Washington, and in Florida. But when, in our conversation, the subject turned to the contemporary Supreme Court Stevens’s tone darkened.

I asked him if the center of gravity had moved to the right since he became a Justice. “There’s no doubt,” he said. “You don’t have to ask me that. Look at Citizens United.” He added, “If it is not necessary to decide a case on a very broad constitutional ground, when other grounds are available, then doesn’t that create the likelihood that people will think you’re not following the rules?”

Stevens doesn’t pretend that he’s more in tune with the Court than he is. When I asked him if there were any cases he especially regretted, he said, “Dozens. There are a lot I’m very unhappy with.” The first two that came to mind: District of Columbia v. Heller, in which the Court, in 2008, recognized an individual’s right to own weapons under the Second Amendment; and Bush v. Gore, halting the recount that the Florida Supreme Court had ordered in the 2000 Presidential race. He was in the minority in both.

On some subjects, his own views have shifted. Writing on affirmative action, in 1980, he noted, “If the National Government is to make a serious effort to define racial classes by criteria that can be administered objectively, it must study precedents such as the First Regulation to the Reich’s Citizenship Law of November 14, 1935”; yet in 2003 he engineered the preservation of racial preferences in admissions in a case involving the University of Michigan Law School. In 1976, he joined his colleagues in ending a moratorium on the death penalty; in 2008, he wrote that executions are “patently excessive and cruel and unusual punishment violative of the Eighth Amendment.” Stevens has always supported abortion rights and an expansive notion of freedom of speech.