WASHINGTON -- Justice Harry A. Blackmun's retirement this summer will leave the Supreme Court with one obvious gap: It will have no judge willing to keep a thumb on the scale of the law to make it weigh in favor of "the little people."

That is how Justice Blackmun has seen his job for years, that is what has led most court observers to label him a "liberal," and that is why he sometimes is criticized for appearing to opt for results more than for legal principle.

Without a justice inclined that way, the court after Justice Blackmun is likely to be seen as moving even further toward the center of the judicial spectrum -- a center revolving around the idea that the law is not meant to be an engine of social reform. Reform, in that view, is primarily for legislatures, not courts.

A dozen years ago, Justice Blackmun objected to a headline that said he "leads the court to the left." He said: "Well, we all know headlines, and that just isn't true."

But his presence on the court, and his view of the law as a safeguard for hapless individuals who get caught up in government rules or prohibitions, has been far more pleasing to liberals on the left than to conservatives on the right.

After the court's self-proclaimed liberals, such as Justices William J. Brennan Jr., William O. Douglas and Thurgood Marshall, had departed, Justice Blackmun remained the one justice who could be counted on to speak out and write vigorously to promote the same kinds of results. He never served on the court with the late Chief Justice Earl Warren, but he was a philosophical heir of the decidedly liberal Warren years in the 1950s and 1960s.

No disciple likely

Now, none of the potential nominees figuring in speculation about a new justice, and no nominee with any chance of emerging from President Clinton's selection process, would be likely to approach the task of judging according to what might be called "Blackmun's law."

Although Justice Blackmun has been considered a legal scholar good at employing the language and the logic of the law, he has been stirred more often -- in cases he thinks will affect the powerless or the deprived or the needy -- by broad notions such as "decency and human dignity" or "the precepts of civilization we profess." Those are social or even moral value phrases more than they are legal; they are phrases that Justice Blackmun has used to describe his view of law's highest function.

And, as his most predictable adversary within the court, Justice Antonin Scalia, has complained, such phrases are so open-ended that they release justices to create, rather than follow, the law.

Those sweeping phrases do not show up routinely in the writing of the other liberal-oriented justice still sitting, John Paul Stevens. He votes often with Justice Blackmun, but the law according to John Stevens is far more disciplined, less expansive and more traditional.

The Blackmun approach is one that more often than not finds government power to control individuals' lives to be wrong or even excessive, and leads more often to a kind of "loose construction" of the law.

It has gotten Justice Blackmun into trouble with critics for the way it led him to view a right of privacy, only loosely anchored to actual words in the Constitution, as the basis for a woman's right to seek an abortion with only her doctor's consent.

The abortion decision, Roe vs. Wade, did not start out in Justice Blackmun's contemplation as a profound act of constitutional creation, and he never saw it as that. His first drafts of that decision, in fact, were narrow applications of past precedent.

But, as he spent weeks closeted in the library of the Mayo Clinic in the summer of 1972, looking searchingly into the bond between a woman and her obstetrician, he saw that relationship as a social equation demanding privacy against government control.

He often has railed against the argument that the ruling gave women sole and complete autonomy over their bodies -- the argument made by anti-abortion forces who regard Roe vs. Wade as totally lawless.

Constitutional equation

Those forces also have complained that the decision allows the destruction of the life within a pregnant woman's body. But Justice Blackmun could find neither law nor philosophy to make that life pre-eminent in the constitutional equation between a woman and her doctor.

When three of the court's currently dominant bloc of centrist justices led the court to reaffirm part of Roe vs. Wade two years ago, their decision did not follow "Blackmun's law." It instead held to the more pragmatic and traditional legal notion that settled law is better than unsettled law. The combined opinion prepared by those three justices -- Anthony M. Kennedy, David H. Souter and Sandra Day O'Connor -- made clear that they sought simply to end "a jurisprudence of doubt" that had grown up around the law of Roe vs. Wade.

In fact, their ruling perpetuated only a bare minimum of Roe and went on to overrule a classic example of "Blackmun's law": a 1986 post-Roe precedent that Justice Blackmun had written to nullify virtually any state law enacted with the aim of discouraging abortion.

Roe vs. Wade, and the sequel he wrote in 1986 (and that lasted for six years), obviously were not all that Justice Blackmun has written in his 24 years as a justice. But no other opinions display as clearly his way of deciding.

The justice believes, as he said yesterday, that he has not changed over the years. Noting that he and Justice Stevens recently joked about how they were considered the remaining liberals, he said they agreed that "neither of us has changed; the court has changed under us."

Taking it personally

Whether the most famous of Justice Blackmun's judicial writings show a change or merely a progression, there is something they clearly do not show: the degree to which "Blackmun's law" was something that the justice took personally.

When he is on the bench, with his few verbal interventions, and when in private, Justice Blackmun shows how caught up he is in the plight of what he called -- meaning no insult -- "the little people."

He would try to see through legalisms to human detail, to the pain, the loss, the denial that he could trace to legal commands or even to legal neutrality. At those times, he would seem far more sentimental than judicial.

He would interrupt a lawyer, in the midst of a flowing legal argument, to ask what a scene really looked like, or how the people involved had reacted. He even asked one lawyer if she had read a particular novel that would have given human meaning to her legal points.

In public, he always has seemed profoundly serious. That, too, failed to reveal another part of what Harry Blackmun is like. It would not show the pixie who, for example, would deliberately fail -- for days -- to tell his colleagues that the electronic buzzing they had heard during a secret conference could be traced to his hearing aid, rather than to what Justice O'Connor suspected was an illegal "bug" in the room.

Some of that subtle sense of humor showed up yesterday as he described to reporters how his life as a justice has been lived in the midst of a family of females: a wife and three daughters, and "even a female dog, for a while." All but one of them, he said, supported his decision to retire. He did not say which one objected.