Until about a decade ago there was a park bench in a small town on the New Jersey side of the Hudson which bore the sign ''Impeach Earl Warren.'' The message, heralded there and across the United States in various forms during the 1960s, was sponsored by the John Birch Society. In the eyes of many right-wing critics, the late chief justice of the United States represented court endorsement for what they considered permissive, immoral, and left-leaning judicial practices.
Ironically, Mr. Warren was a Republican with a significant conservative track record as state attorney general and governor of California, before being elevated to chief justice in 1953 by another Republican, Dwight D. Eisenhower.
It was Earl Warren, however - the ''liberal'' justice, the trailblazer for many modern civil rights decisions, and the shaper of Supreme Court policy - that his critics were most concerned about.
And well they should have been. Today, almost 15 years since the Californian left the bench, Warren-led judicial decisions still pervade court philosophy, despite the newer appointments to the court by Republican presidents and a tilt to the right by the US electorate.
How is this possible? And will it continue?
Answers, or at least keys to answers, are provided by Bernard Schwartz, a prestigious legal scholar and author of more than two dozen books, including a new, monumental volume, ''Super Chief: Earl Warren and His Supreme Court - A Judicial Biography'' (New York University Press). Schwartz breaks new ground in the book - showing inner workings of the court, via previously unpublished letters, notes, memos, and even authenti-cated reports from the justices' highly secret judicial conferences.
The reporter spoke with Professor Schwartz in his Washington Square office here, in between his NYU Law School classes and professional appearances. He talked about Earl Warren's impact on the court itself and on the judiciary today. And he looked at the structure, composition, and workings of the Supreme Court - examining consequences if the Warren influence were suddenly to wane.
Schwartz's mod-est faculty office, cluttered with casebooks, research papers, and other trappings of academia, belies his easy-going countenance and an ability to communicate with the layman. This ability is evident in a second book that grew out of the 853-page ''Super Chief.'' Eager to reach readers outside the legal community, Schwartz collaborated with Newsweek correspondent Stephan Lesher to produce an abridged, lay-oriented version of his analysis, ''Inside the Warren Court'' (Doubleday).
Professor Schwartz insists that Warren's stamp on the court was significant enough to place him alongside some of the more highly heralded chief justices in US history. Schwartz says Warren succinctly framed arguments, led his associates down carefully blazed judicial paths, and proved a worthy debater for the intellectual heavyweights among the ''brethren,'' including Justices Felix Frankfurter, Hugo L. Black, and William O. Douglas. ''Most people, even at the time, thought of him (Warren) as a bland, easygoing, political type who really didn't have any depth to him,'' Schwartz explains. ''But when you go over his work in the court, you see he was a true leader.''
According to this biographer, Warren was a ''representative of Middle America. He could have come out of Sinclair Lewis or Sherwood Anderson.'' Warren was also a brilliant jurist. ''When he got to the court, he really led. . . . He had an instinctive way'' about him.
Schwartz chronicles how the chief justice engineered a unanimous court decision in Brown vs. Board of Education, the landmark school desegration case, turning the court from a 5-to-4 split to a firm stand for integration. ''It would have been disaster for the country had the case come down with a bare majority, whichever way it went,'' the legal scholar explains. He says Warren - in this instance and time and time again - mobilized support for key civil rights issues by the way he framed them in the judicial conference. ''The chief justice sets the stage'' in the forum of the court, Schwartz says. ''If he is effective, the justices will act one way. If he is ineffective and doesn't set a tone, there will be all kinds of dispute and confusion, and the court will be atomized,'' he says.
Although the Warren court led the way on racially related education issues, privacy matters, First Amendment religious freedom, and press-rights issues, many landmark liberal decisions did not actually come until the 1970s, after Earl Warren retired. Ironically, the more conservative Burger court (named after the current chief justice, Warren Burger) is seen by some legal scholars as more responsive to individual rights and liberties than any of its predecessors.
Schwartz is quick to point out, however, that many contemporary court decisions - restricting the use of the death penalty, protecting abortion rights , and upholding affirmative action to redress discrimination - were based on Warren-era precedents.
The link between the court of the 1960s and the 1980s is Justice William J. Brennan, a veteran liberal who played a particularly prominent role on the Warren court.
Dennis J. Hutchinson, a University of Chicago law professor assessing ''Super Chief'' in the Michigan Law Review, writes: ''When the public record is added to Schwartz's numerous behind-the-scenes examples of managing the court, Brennan emerges clearly as the most important justice of the period.''
Schwartz points out that Brennan had the facility to find common legal ground among majority opinions of various justices. For example, in a key 1965 case, Griswold v. Connecticut, which challenged state law banning married couples from acquiring birth-control devices, Brennan persuaded Justice Douglas to abandon a ''freedom of association'' argument for invalidating the statute and to rely instead on the constitutional right to privacy. The latter not only provided a theory that satisfied the majority of the Warren court, says Schwartz, but also protected single people. More important, the biographer insists, it gave the Burger court a basis for invalidating state abortion laws in recent years.
Comparing the present court with the Warren reign, Schwartz points out how Brennan's liberal influence has waned in a more conservative tribunal. ''Now he speaks so often in dissent. In the Warren court, particularly in the later years , he almost never dissented.''
More broadly, Professor Schwartz says, the Burger court doesn't fit into a logical pattern, as did the Warren court. If, in considering Warren court decisions, ''you look at each decision as a dot, as I sometimes do, and then draw the lines together, you get a picture. . . . With the Burger court you get abstract art,'' Schwartz says.
The judicial scholar further describes today's court as ideologically fragmented - with ''two or three on the left, three or four in the center, and two or three on the right,'' depending on the issue. ''It's much harder to guess the decisions under this court than to guess what the decisions under the Warren court would be,'' he says.
But lack of a clear judicial philosophy could give way to strong conservative leanings if President Reagan has the opportunity to appoint new justices, either before or after next year's presidential election. Justice William Rehnquist and President Reagan's appointee, Justice Sandra Day O'Connor, are now considered the most right-leaning members of the court. They are also the youngest, likely to serve for years to come. On the other hand, among those with a more liberal philosophy, Brennan and Justice Thurgood Marshall are well past normal retirement age.
Chief Justice Burger, who usually shares the Reagan philosophy, has hinted he might retire. And some scholars think he might even time his exit to allow the current President the opportunity to choose his successor.
''The next president may have more appointments than any (chief executive) since Dwight D. Eisenhower,'' Schwartz points out. And this could mean a complete changeover, he says.
Schwartz predicts that if Reagan is reelected, however, he will appoint ''conservative purists. One thing these justices are going to believe in is adherence to precedent. And this is going to mean a reluctance to have dramatic changes.''
He adds that there is likely to be a trend - no matter who the next president is - toward ''keeping hands off'' issues that justices feel ''should be decided by the state courts first.'' Justice O'Connor already leans strongly in this direction. This leaning is dictated not only by philosophy, Schwartz explains, but by the burgeoning caseload in all the federal courts.
Chief Justice Burger has suggested that a temporary intermediate court be set up to help the high court sort out federal cases while a congressional commission studies broader recommendations for alleviating the growing burden on the Supreme Court. Schwartz advocates eliminating the requirement that those state cases in which there is so-called ''diversity jurisdiction'' be decided by the federal judiciary.
Despite its shortcomings, the legal system works well, Schwartz says. And he insists that, over the years, the high court and other federal courts have ably ''protected the rights of those who cannot get protection elsewhere.''
Justices are not fighting for better position, personal remuneration, or other personal advancement, he points out. ''They have no place else to go. Their only goal is to decide the cases with the views they believe in.''