This one is not just another Supreme Court retirement.

It is not just another new vote, not just another chance to tip the court's balance this way or that on one issue or another.

Justice William J. Brennan Jr., who announced his retirement Friday, was the chief living practitioner of a style, an approach, a method of judging that reached out to right perceived wrongs, wore its values on its sleeve and changed the course of American history.

Call it "humanist." Call it "activist." Call it the "Warren Court" approach.

Love it or hate it, Brennan perfected it, and helped it endure two decades beyond the retirement of Chief Justice Earl Warren. From it flowed the principle of "one man, one vote"; constitutional protections for women; a ban on public aid to religious schools; the legalization of abortion; protections for welfare recipients and prison inmates, and for purveyors of rudeness, lewdness and nudity; for killers, flag-burners, whistle-blowers and fire-breathers of every imaginable stripe. It opened doors in the federal judiciary for arguments and issues once flatly barred from entry.

Brennan's retirement signals the ascension of a very different approach. "Reaching out," to its adherents, is the business of legislatures, not judges. They believe values should be expressed through the ballot box, not at the bench, and they confront cases asking fundamentally different questions leading to fundamentally different conclusions. The conflict between the two schools is as old as the judiciary, ebbing and flowing with the times and presidential appointments.

The current transition, now well underway, may never be complete. The approach cultivated by the Warren Court has penetrated too deeply into case law and the skulls of generations of law students, lawyers, judges and politicians.

Brennan, even to those who disagree with the Warren approach, has had a profound impact on more than just American jurisprudence. "Brennan is in a different league than other judges," said Charles J. Cooper, assistant attorney general in the Reagan administration and an architect of much conservative Reagan legal policy. "In the time frame of this half century, he towers above every other individual who has been in public life. There's no president who has had the influence on public policy" that Brennan has had.

"I can think of no one on the court who had more influence in shaping the modern Supreme Court than Bill Brennan," said A.E. Dick Howard, University of Virginia law professor.

The genius of Brennan -- the skill that made him more equal than his equals on the court -- was that as he crafted his opinions he worried about the analysis, knowing that it would endure longer than the result, and would be applied over and over again at all levels of the judiciary.

His battle to give constitutional protection to women is illustrative. Until Brennan's rulings in the 1970s, states could, and did, treat women differently than men in a variety of ways, imposing varying requirements for everything from beer drinking to alimony.

Though nothing in the Constitution explicitly prevented this, Brennan held that distinctions based on gender could survive only if "substantially related to the achievement of an important governmental objective." This subjected gender distinctions to a higher level of court scrutiny.

Brennan's theory, fumed Justice William H. Rehnquist, "apparently comes out of thin air. . . . I would have thought that if this court were to leave anything to decision by the popularly elected branches of the government, it would be this."

Although the court did not go as far as Brennan would have liked, the theory became the law, and discriminatory statutes were overturned across the nation -- without ratification of any Equal Rights Amendment.

It is "an approach to judging that will be losing its most important practitioner," said Cooper, a former Rehnquist clerk. "It is understandable why liberals are rending their garments and conservatives are respectfully applauding."

Even when Brennan lost, he often won something. He waged war against the death penalty throughout his 34 years on the court, but was never able to get a court majority to agree with him that capital punishment is unconstitutional. Still, he and his allies slowed the process to a relative crawl by erecting so many procedural hurdles for states that even today less than 5 percent of the thousands of people sentenced to death in the past two decades have been executed.

Brennan's approach to capital punishment illustrates the difference between his approach to judging and that now in ascendance. He never argued that any specific language in the Constitution even hinted that capital punishment should be banned. Rather, the Eighth Amendment's ban on cruel and unusual punishment, he wrote, "embodies in unique degree moral principles restraining the punishments that our civilized society may impose on those persons who transgress its laws." The court "inescapably has the duty" to bring "moral concepts" to bear on the issue, he wrote.

To judicial conservatives, the "inescapable" duty of the court, when it lacks explicit guidance from the Constitution, is to defer to the elected branches of government rather than to "moral concepts." To do otherwise, they say, is the very essence of activism.

Even judicial moderates, like Howard, raise their eyebrows at some of Brennan's views. "I've had hours and hours" of interviews with him for a public television series, Howard said. "I thought it {his death penalty stand} was his longest stretch. These cases came nearest to reflecting an a priori judgment on Brennan's part . . . asserting a value and saying this is what the Constitution means."

No one is pure in this long-running struggle over judicial philosophy, and activists abound on all sides. But the gap in outlook between the liberal and conservative approaches is nonetheless vast and of enormous consequence for litigants and for the nation. Warren-era judges, like Brennan, ask whether anything in the Bill of Rights explicitly prevents them from offering its protection to the individual. The burden is on the government to show that someone said "no."

Judges who take pride in "judicial restraint" ask whether anything in the Constitution or in the precedents explicitly permits them to extend protection. The burden is on the individual to show that someone said "yes."

When it comes to government power, on the other hand, the liberal activist judges reverse the coin. They tend to ask, when state power is challenged, whether such power draws its authority from any explicit constitutional or statutory declaration. If not, they look askance. The conservative judges ask whether anything in the law prevents government from bringing its power to bear. If not, it is permissible.

Brennan and the other Warren-era judges were not afraid to cross boundaries into areas previously considered off-limits for the federal courts. Before 1962, for example, the fairness of legislative apportionment in the states was considered a "political question" -- the business of elected leaders, not judges. In Baker v. Carr, an opinion that may be Brennan's most important, the court stepped across that line.

Nothing, Brennan concluded for the majority, prevents us from doing so.

The pure "strict constructionists" wade through the Constitution, along with the laws, the debates of the nation's founders and the precedents, to find guidance. They say they go by the book, and if it's not there they rule accordingly.

But Brennan, especially in his writings and speeches, confesses unabashedly to a humanist approach. The Bill of Rights, he said in a 1966 speech, is not just words. It's "an arsenal for achieving human brotherhood."

"Our task," Brennan said in an interview long ago, "is to interpret and apply the Constitution faithfully to the wisdom and understanding of the Founding Fathers. But often it is impossible to make a constitutional decision without basing certain findings on data drawn from the social sciences, from history, geography, economics and the like."

Brennan had brains, skill, single-mindedness of purpose and powerful ideas. There is no debate about that. But virtually all who knew him or worked with him attribute his singular role on the court to something more visceral as well, something they say cannot be understated and is not mere tribute.

"I don't think you can account for Justice Brennan's influence without saying this," Howard said. "He was a warm, charming, gregarious, universally loved member of the court. I've known a lot of justices," said Howard, who clerked at the court for two terms, "and I can think of no justice who has enjoyed more respect and affection. Coupled with his tactical skill, his uncanny mechanical skills and his political instincts, one gets a most effective justice."

"He is a lovable man," said Cooper, an ideological archenemy of Brennan. "You cannot dislike this man on a personal level, no matter how destructive he's been to the values you hold dear.

"He was grasping my arm tight against his chest as we walked to lunch one day when I was a law clerk." It is pure charm, said Cooper, and "one of the reasons he's been so awesomely successful at influencing others."