POTTER STEWART IS DEAD AT 70; WAS ON HIGH COURT 23 YEARS

Potter Stewart, an Eisenhower Republican from Ohio who spent 23 years on the Supreme Court, died yesterday in a hospital in Hanover, N.H., where he had been admitted after suffering a stroke. He was 70 years old.

Milner E. Noble, a spokesman for the Dartmouth-Hitchcock Medical Center, said Associate Justice Stewart died at 3:20 P.M. He had been in critical condition since being admitted to the medical center Monday, the spokesman said.

For half of his time on the Court Justice Stewart was a conservative, often dissenting member of the Warren Court; for the other half he was at the decisive center of the more conservative Burger Court.

He preferred a pithy phrase to a long philosophical opinion. He spoke of common sense approaches to problems that sharply split the Court and the country along ideological lines. Modesty and intense loyalty to the institution prevented him from seeking to lead the Court from within and even prompted him to ask a President not to consider him for Chief Justice.

'I Know It When I See It'

As he lamented publicly when he retired in June 1981, Justice Stewart's epitaph could have been his phrase from a 1964 obscenity case: ''I know it when I see it.''

For admitting that he could identify but not define hard-core pornography, he was criticized as unjudicial but praised for candor. Only a few years later he began arguing that judges should stay out of obscenity cases altogether except when the obscenity was blatant or pandered to children.

It was not the only time Justice Stewart made a short, quotable remark. Dissenting in 1966 from what he called a rigid, simplistic enforcement of antitrust laws to halt a business merger, he complained that the decision's only consistency with precedent was that ''the Government always wins.''

In 1972 he explained his vote to strike down state death penalty laws by saying, ''These death sentences are cruel and unusual in the same way that being struck by lightning is cruel and unusual.''

When the Court in 1973 ruled that a debtor could be denied access to the bankruptcy court for want of a $50 filing fee, he quipped: ''The Court today holds that Congress may say that some of the poor are too poor even to go bankrupt. I cannot agree.''

Justice Stewart wrote or joined in many decisions upholding the First Amendment claims of reporters and news organizations, but he also wrote the Court opinion rejecting press rights of access to prisons or pretrial court proceedings. On civil rights issues he followed the Court's school desegregation rulings until he regarded some busing orders as excessive.

In a dramatic departure from middle-of-the-road positions, he delivered the Court's 1968 opinion reviving a Reconstruction-era law against discrimination in real estate sales and other private transactions. He voted for stronger enforcement of fair employement statues but argued for ''colorblind'' interpretations when he saw affirmative action programs leading to racial quotas.

Mr. Stewart had a checkered record on issues of women's rights. He struck down a Virginia law requiring excessive unpaid maternity leave for teachers but upheld state employee disability plans that excluded maternity benefits. He voted reluctantly to concur in the Court's 1973 decision striking down state laws prohibiting abortion but wrote the Court's majority opinion upholding the power of Congress to bar Medicaid payments for abortions.

Regarding the rights of criminal suspects, Justice Stewart usually cast his vote on the side supported by the police and prosecutors, dissenting in such cases as the 1966 Miranda v. Arizona ruling setting strict guidelines for confessions. But when he saw a police intrusion between a defendant and his attorney, as in Massiah v. United States in 1963, he voted to throw out evidence obtained in violation of the right to counsel.

Despite his disagreements with many Warren Court decisions, Mr. Stewart resisted later attempts to overturn them, preferring to limit those rulings. He vigorously dissented in 1974 from an apparent overturning of a two-year-old decision when ''the only perceivable change that has occurred is in the makeup of this Court.'' Two years later he withdrew that charge of Court politicization in a case that, he said, showed his fears had been exaggerated.

Influential Cincinnati Family

Potter Stewart was a member of an influential Cincinnati family. He was born on Jan. 23, 1915, in Jackson, Mich., where his parents had been vacationing. His father, a Cincinnati lawyer, served nine years as the city's Mayor and later became a judge on the Ohio Supreme Court.

Potter earned academic scholarships to preparatory school and college, a Phi Beta Kappa key and cum laude degrees from college and law school. He was a graduate of the Hotchkiss School in Lakeville, Conn., Yale College and, after a year of international law study at Cambridge University in England, Yale Law School.

He spent two college summers on a Cincinnati newspaper and was chairman of The Yale Daily News, but the only interruption on his path to a law career was service in World War II as a naval lieutenant aboard oil tankers.

Mr. Stewart practiced law in New York briefly before and after World War II. He returned to Cincinnati in 1947, joined a leading law firm and pursued an interest in politics. He served two terms on the City Council and was the city's vice mayor for two years. Senator Robert A. Taft Jr. was a family friend, but Mr. Stewart leaned toward Dwight D. Eisenhower for the 1952 Republican Presidential nomination.

Became Youngest Federal Judge

When President Eisenhower named him to the United States Court of Appeals for the Sixth Circuit in 1954, Mr. Stewart was 39 years old, the youngest Federal judge in the country.

Perhaps his most famous circuit court opinion was issued just two weeks before his Supreme Court appointment in 1958 from the Second Circuit Court of Appeals in New York, where he sat briefly as a visiting judge.

The case grew out of a libel suit by Judy Garland, the singer, against Marie Torre, television columnist for The New York Herald Tribune. Judge Stewart held that whatever First Amendment right the columnist might have to preserve the confidentiality of her sources, she was required to divulge the source of defamatory remarks about Miss Garland that apppeared in her column or serve a jail sentence for contempt of court. Miss Torre went to jail.

On Court Before Confirmation

After the retirement of Associate Justice Harold H. Burton, President Eisenhower appointed Judge Stewart during a Congressional recess, in October 1958, permitting him to join the Court before the Senate confirmed him the following May. At 43, he was the second youngest appointee since before the Civil War; William O. Douglas was 40 when he was appointed in 1939.

The Court that Justice Stewart joined was closely divided on many of its most important questions, which often gave the junior member the deciding vote in his first few years. Although his vote was often sought by either side, he rarely indulged in internal lobbying for the votes of others. He also established early the practice of deciding most cases on the narrowest grounds with a minimum of judicial philosophizing. He spoke of labels like liberal and conservative as ''fatuous,'' and when asked to describe himself, he said he thought of himself primarily as ''a lawyer.''

One of his first major opinions for the Court, a 5-to-4 decision in a case called Shelton v. Tucker, was important to constitutional law but somewhat limited in scope. He ruled that an Arkansas law requiring public school teachers to list every association or group membership violated the First Amendment.

It was one of a series of decisions laying down the principle that even when Government is entitled to information, it must proceed carefully and no more intrusively than necessary when freedom of speech, press, religion and association are involved.

Resisted Officiousness

Another Stewart theme was resistance to Government officiousness and the tendency of the police and officials to bother people with divergent beliefs or ways of life. In 1961 he dissented when the Court upheld a Sunday closing law in Pennsylvania, saying it forced an Orthodox Jew who wanted to observe his Sabbath and do business on Sunday ''to choose between his religious faith and his economic survival.''

''That is a cruel choice,'' he wrote. ''For me this is not something that can be swept under the rug and forgotten in the interest of forced Sunday togetherness.''

Justice Stewart was the lone dissenter when the Court struck down compulsory prayer recitations and Bible-reading in public schools as an unconstitutional establishment of religion. He argued that the state also had a right to support individuals in their constitutional right to free exercise of religion. He said later that he was embarrassed by the flood of fan mail he received from writers who assumed he was expressing deep religious conviction rather than his view of the Constitution.

He warned that ''government by big brother'' was near when the Court, in Ginzburg v. United States in 1966, upheld an obscenity conviction out of what he called personal distaste for the defendant's ''sordid business'' of hawking sexy magazines.

'No Power to Pick or Choose'

He argued in dissent: ''The First Amendment protects us all with an even hand. It applies to Ralph Ginzburg with no less completeness and force than to G. P. Putnam's Sons. Putnam's was the publisher whose right to distribute the novel ''Fanny Hill'' was upheld the same day.

When the loitering ordinance of his hometown of Cincinnati came before the Court in 1971, Justice Stewart objected to its loose language forbidding conduct that was ''annoying'' to others. He struck it down as a violation of both due process and the right of peaceable assembly.

In O'Connor v. Donaldson, a major 1975 mental health case, Justice Stewart held that states may not confine the insane involuntarily if they are not dangerous and can live safely out of institutions.

Defendant May Represent Himself

A week after that decision, the Justice delivered the Court's opinion in Farretta v. California, saying the state does not always know best when a defendant wants to represent himself without a lawyer. If the accused is mentally competent and willing to take the risk, courts should not stop him.

''To force a lawyer on a defendant can only lead him to believe that the law contrives against him,'' he wrote.

In civil rights, Mr. Stewart delivered two opinions with different results growing out of the same 1963 demonstrations in Birmingham, Ala. He ruled in 1967 that even if the city's parade-permit ordinance was unconstitutional, the demonstrators could not violate a court injunction enforcing it. In 1969 he ruled that the same ordinance, properly tested on review of convictions for violating it, was unconstitutional. The Court's clear message: test laws in an orderly way, without defying courts, and you have a chance of winning.

His most far-reaching civil rights decision came in the 1968 case of Jones v. Mayer Co., involving a lawsuit by a black St. Louis man who was rebuffed when he tried to buy a suburban home. A law giving blacks new property rights after the Civil War had lain dormant because of 19th-century Supreme Court decisions that, Justice Stewart said, were based on an overly restrictive reading of the Constitution. Revived, the law was a more sweeping ban on private housing discrimination than Congress was able to pass a century later.

Proud of the Opinion

Justice Stewart was asked by the librarian of Hofstra Law School to name his favorite case. He cited Rideau v. Louisiana but did not elaborate. That was a 1963 opinion reversing a murder conviction because jurors had been influenced by television broadcasts of the defendant confessing to the sheriff.

Justice Stewart was part of the six-member majority in the 1971 Pentagon Papers case that ruled out court injunctions against publication of the Defense Department's secret history of the origins of the Vietnam War. Although the Justices' opinions split in many directions, his opinion, joined by Justice White, expressed the prevailing view that only material that would certainly cause ''direct, immediate and irreparable damage to the nation or its people'' could be restrained by courts before publication.

He summarized the state of First Amendment law in a candid address at the Yale Law School in 1974.

''So far as the Constitution goes,'' he said, ''the autonomous press may publish what it knows and may seek to learn what it can. There is no constitutional right to have access to particular government information or to require openness from the bureaucracy. The Constitution itself is neither a freedom of information act nor an official secrets act. The Constitution, in other words, establishes the contest, not its resolution.''

Rulings on Women's Rights

Justice Stewart sought but rarely found a middle ground on issues raised by women's rights organizations.

His opinions on contraception and abortion disclosed strong personal views against restrictive state laws -he called Connecticut's contraceptive statute ''uncommonly silly'' - but an inability to find a constitutional basis for striking them down. His concurring opinion in the Roe v. Wade abortion decision in 1973 called on his colleagues to acknowledge the revival of so-called ''substantive due process'' - a lawyer's term for judges' substituting their personal values for those of the legislature. His reservations persisted throughout his Court service. He cast the deciding vote and delivered the 1980 opinion, in Harris v. McRae, that legislatures need not include abortion funding in medical benefits.

In criminal law, Justice Stewart's 1972 vote against capital punishment laws was based on what he considered unequal application of the death penalty. In 1976 he voted with two other centrist Justices, Lewis F. Powell Jr. and John Paul Stevens, to control the results of five major test cases. With the Court's other members holding firm views totally for or against five newly re-enacted death penalty laws, the centrist justices voted to uphold Georgia, Florida and Texas laws while striking down mandatory execution laws in North Carolina and Louisiana.

Sought Narrowest Grounds

Justice Stewart's quest for the narrowest possible grounds for decision was exemplified in 1961 when he ruled that the police had violated the Fourth Amendment by driving a wired ''spike mike'' through the wall of a Washington townhouse to overhear conversations of gamblers next door. Urged to abandon privacy concepts that depended on whether the police physically trespassed on the suspects' private property, Mr. Stewart said the case could be decided by adhering to the traditional dividing line, adding, ''But we decline to go beyond it, by even a fraction of an inch.''

Six years later he cited that decision as part of the ''eroding'' of old privacy doctrines, overruled two precedents and declared, in Katz v. United States, that a microphone placed against an outside wall could be an invasion of privacy. As usual, he summed it up in a phrase: ''The Constitution protects people, not places.''

Justice Stewart was outspoken in the courtroom, asking pointed questions of lawyers during arguments. After many other justices had abandoned the practice, he delivered entire majority opinions or dissents orally from the bench when he considered them important.

A Secret Call on Nixon

In 1969 he took a dramatic step to insure that he would not be named Chief Justice. Amid press speculation that he might be elevated to replace the retiring Earl Warren, he made a secret call on President Nixon. He told the President that history had taught that it was unwise to promote Associate Justices and that it was prudent to name a Chief Justice from outside the Court. Some historians have disputed Justice Stewart's contention, but he feared strained internal relationships at the Court.

After Mr. Nixon disclosed the meeting, Justice Stewart explained that he had spoken to the President in part to put aside any personal ambition he might harbor, keeping a promise to himself not to seek any higher office once he had reached the Court. Justice Stewart recalled that after his White House visit ''I felt better than I had felt in a long time.''

His retirement at age 66 - only Justices Sherman Minton and Charles E. Whittaker retired at younger ages -was a surprise when it was announced just before the close of a Court term in 1981. Any of five older Justices could have been expected to retire sooner. Justice Stewart explained that he had been thinking of quitting - but taking on special assignments on lower courts - soon after he became eligible the previous year but that he had put off retiring to avoid an election-year confirmation fight over his successor.

Justice Stewart became better known to many Americans in his retirement, when he appeared with Fred W. Friendly in a public broadcasting series on the Constitution.

Justice Stewart is survived by his wife, Mary Anne; three children, Potter, David and Harriet Virkstis; a sister: Irene Bernard, a brother, Zeph, and six grandchildren. ----Praise for Stewart WASHINGTON, Dec. 7 (AP) - Justice Stewart was mourned today as ''a patriot and a good lawyer - indeed, a brilliant man of the law'' by President Reagan, who said the Justice had lived a ''magnificent life.''

Chief Justice Warren E. Burger said in a statement issued by the Court that the death ''removes a splendid jurist from the bench.''

''For more than two decades Justice Stewart gave dedicated and distinguished service to our country,'' he said.

Vice President Bush called Justice Stewart ''an outstanding man'' who was a symbol of decency and honor. ''He was a constitutional scholar who interpreted the Constitution without succumbing to the temptation to legislate from the bench,'' Mr. Bush said.