Justice Potter Stewart served as an Associate Justice of the United States Supreme Court for twenty-three years, from 1958 to 1981, and left his mark on American constitutional law through landmark rulings on privacy, obscenity, capital punishment, and press freedom. He wrote the majority opinion in Katz v. United States, joined the fractured majority that halted executions nationwide in Furman v. Georgia, and produced one of the most quoted lines in Supreme Court history when he wrote that he could not define hard-core pornography but “I know it when I see it.” His refusal to align consistently with either the liberal or conservative wing made him a frequent swing vote and one of the most closely watched justices of his generation.
From Cincinnati to the Supreme Court
Stewart was born on January 23, 1915, in Jackson, Michigan, and grew up in Cincinnati, Ohio. He graduated from Yale College in 1937, studied for a year at Cambridge University in England, and returned to Yale for law school, graduating in 1941. After a brief stint at a New York firm, he served as a lieutenant in the United States Navy during World War II.
Back in Cincinnati after the war, Stewart entered private practice and local politics. He won election to the city council in 1949 and again in 1951, serving one term as vice mayor. In 1954, President Dwight D. Eisenhower appointed him to the United States Court of Appeals for the Sixth Circuit, making him one of the youngest federal appellate judges in the country.1Federal Judicial Center. Stewart, Potter Four years later, Eisenhower gave him a recess appointment to the Supreme Court on October 14, 1958. The Senate confirmed him on May 5, 1959, by a vote of 70 to 17.2Justia. Justice Potter Stewart
How He Decided Cases
Stewart resisted ideological labels. He occupied a middle position on a Court that shifted dramatically around him, first under Chief Justice Earl Warren’s liberal majority and then under Chief Justice Warren Burger’s more conservative leadership. Rather than applying a grand constitutional theory, he tended to resolve cases on their specific facts, preferring narrow holdings that left future questions open. That made him difficult to predict. In closely divided cases, his vote often decided the outcome.
The approach frustrated both sides. Liberals wished he would join them more consistently in expanding individual rights. Conservatives found him unreliable when they expected deference to government authority. Stewart saw the independence as the point. He once told an interviewer that he did not think of the Court’s work in liberal or conservative terms; the question was always whether the Constitution compelled a particular answer in a particular dispute.
“I Know It When I See It”
Stewart’s most famous line came from Jacobellis v. Ohio (1964), which reviewed the conviction of a movie theater manager who had shown a French film called “Les Amants” (“The Lovers”).3Justia U.S. Supreme Court Center. Jacobellis v. Ohio, 378 U.S. 184 (1964) The question was whether the film qualified as obscene material unprotected by the First Amendment. Stewart concurred that it did not, and his reasoning was strikingly candid. The Constitution, he wrote, permitted governments to ban only hard-core pornography, and he would not try to define that category further: “I know it when I see it, and the motion picture involved in this case is not that.”
The line became legendary because it captured the problem the Court could not solve. Roth v. United States (1957) had tried to set an objective test, but the justices spent the next decade disagreeing about how to apply it. Stewart’s concurrence effectively narrowed the scope of unprotected material to the most extreme content while giving lower courts little practical guidance. The struggle continued until 1973, when the Court adopted the three-part test from Miller v. California.4Justia U.S. Supreme Court Center. Miller v. California, 413 U.S. 15 (1973) Stewart’s candor about the limits of judicial reasoning on this topic, though, is more widely remembered than the test that eventually replaced his approach.
Reshaping the Fourth Amendment in Katz
Stewart’s most lasting doctrinal contribution came in Katz v. United States (1967). He wrote the majority opinion overturning the conviction of a man whose phone conversations the FBI had recorded by attaching a listening device to the outside of a public telephone booth. The government argued that because agents never physically entered the booth, no “search” had occurred under the Fourth Amendment. Stewart rejected that reasoning in a line that reframed the entire field: “The Fourth Amendment protects people, not places.”5Justia. Katz v. United States, 389 U.S. 347 (1967)
Before Katz, courts had treated the Fourth Amendment almost like a property-rights provision. Government agents needed a warrant only if they physically trespassed on someone’s property. Stewart dismantled that framework by holding that what a person “seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected.” Justice John Marshall Harlan II’s concurrence then translated the principle into a workable two-part test: a person must have shown an actual expectation of privacy, and that expectation must be one society is prepared to recognize as reasonable. Courts adopted Harlan’s formulation as the standard, but it rests on the foundation Stewart’s majority opinion built. The decision ensured that privacy protections could keep pace with electronic surveillance technology that required no physical intrusion at all.
From Griswold to Roe
Stewart’s thinking about privacy evolved in a revealing way. In Griswold v. Connecticut (1965), he dissented from the Court’s decision striking down a state law banning the use of contraceptives. His dissent was bracingly honest. He called the law “an uncommonly silly law” and said he personally believed contraceptive use should be a matter of private choice. But he could not find anything in the Constitution that prohibited a state from enacting it, and he accused the majority of reviving the discredited doctrine of substantive due process to reach a result they liked.
Eight years later, in Roe v. Wade (1973), Stewart reversed course. Writing a concurrence, he acknowledged that after Griswold, substantive due process could no longer be dismissed. He described the “liberty” protected by the Fourteenth Amendment as a broad concept, one that included “freedom from all substantial arbitrary impositions and purposeless restraints.” The decision to end a pregnancy was personal enough, he concluded, that a rigid criminal ban like the Texas statute at issue amounted to a constitutionally intolerable invasion of that liberty. The same justice who rejected substantive due process in 1965 had accepted it by 1973, once he concluded that Griswold had made the doctrine a permanent part of constitutional law.
Death Penalty: Furman and Gregg
Stewart’s votes on capital punishment followed his case-by-case philosophy to dramatic effect. In Furman v. Georgia (1972), he joined four other justices in striking down every existing death penalty statute in the country. Each justice in the majority wrote separately. Stewart’s concurrence became the most quoted: the death sentences before the Court were “cruel and unusual in the same way that being struck by lightning is cruel and unusual,” because the system imposed them so randomly and infrequently that receiving one was essentially arbitrary.6Justia U.S. Supreme Court Center. Furman v. Georgia, 408 U.S. 238 (1972) The decision halted executions nationwide and forced every state with capital punishment to rewrite its laws.
Four years later, Stewart wrote the lead plurality opinion in Gregg v. Georgia (1976), upholding a new generation of death penalty statutes. Georgia’s revised system addressed the arbitrariness problem through three procedural safeguards: a bifurcated trial where guilt and sentencing were decided in separate proceedings, a requirement that the jury find at least one specific aggravating circumstance before imposing death, and automatic appellate review of every death sentence.7Justia U.S. Supreme Court Center. Gregg v. Georgia, 428 U.S. 153 (1976) Stewart concluded that these guided procedures, combined with the opportunity to present mitigating evidence, satisfied the Eighth Amendment. The ruling allowed executions to resume in the United States.
The two cases together show how Stewart thought about constitutional questions. He did not oppose the death penalty as inherently unconstitutional, nor did he view it as beyond judicial review. The problem in Furman was the process, not the punishment. Once states fixed the process, he was willing to let the punishment stand.
Press Freedom
Stewart took a strong view of press freedom, though not always a majority one. In New York Times Co. v. United States (1971), the Pentagon Papers case, he concurred with the Court’s refusal to block publication of classified Vietnam War documents. His concurrence set a high bar for government censorship: he would permit prior restraint only if disclosure would “surely result in direct, immediate, and irreparable damage” to the nation or its people. The government had not met that standard, so he voted to let publication proceed.8Justia U.S. Supreme Court Center. New York Times Co. v. United States, 403 U.S. 713 (1971)
A year later, in Branzburg v. Hayes (1972), the Court held that the First Amendment did not give reporters a privilege to refuse to testify before grand juries about their confidential sources. Stewart dissented and proposed a three-part test that would have required the government to show probable cause that the reporter had information relevant to a specific crime, that the information could not be obtained through less intrusive means, and that there was a compelling need for it.9Justia U.S. Supreme Court Center. Branzburg v. Hayes, 408 U.S. 665 (1972) The dissent did not carry the day, but Stewart’s framework became enormously influential. Many lower courts and state legislatures adopted variations of it, and it remains the starting point for most discussions of reporter privilege in American law.
Lone Dissents on School Prayer
Stewart was the sole dissenter in two of the Court’s most controversial rulings on religion in public schools. In Engel v. Vitale (1962), the Court struck down a New York school district’s practice of opening each day with a state-composed prayer. Stewart argued that permitting willing students to say a voluntary prayer did not amount to establishing an official religion and therefore did not violate the Establishment Clause. The next year, in Abington School District v. Schempp (1963), the Court invalidated mandatory Bible readings in public schools. Stewart again dissented alone, contending that the record did not establish an Establishment Clause violation and that the cases should be sent back for further hearings to explore whether the practices coerced students who did not wish to participate.
His position in both cases reflected a broader concern that the Court was reading the Establishment Clause too aggressively at the expense of the Free Exercise Clause. Preventing students from praying at all, in his view, could itself burden religious liberty. He did not argue that schools should impose religion on unwilling students. He argued that the Constitution required accommodation, not exclusion, of voluntary religious expression.
Reservations in Reynolds v. Sims
In Reynolds v. Sims (1964), the Court held that both chambers of a state legislature must be apportioned by population, extending the “one person, one vote” principle. Stewart concurred in the result but expressed significant reservations about the sweep of the ruling. He agreed the Court could intervene in extreme cases of malapportionment, but he worried about imposing rigid population-equality requirements on every state.10Justia. Reynolds v. Sims, 377 U.S. 533 (1964) States, he argued, had legitimate reasons to consider factors beyond raw population when drawing legislative districts, and the Court should limit itself to correcting egregious violations of the Equal Protection Clause rather than dictating precise mathematical standards. The caution was characteristic. Even when Stewart agreed with a result, he pushed back against rules he considered too broad for the Court to enforce.
Retirement and Death
Stewart retired from the Supreme Court on July 3, 1981, at age sixty-six, after twenty-three years of service. President Ronald Reagan nominated Sandra Day O’Connor to fill his seat, making her the first woman to serve on the Court.11Justia. Justice Sandra Day O’Connor After leaving the bench, Stewart continued to sit occasionally on federal appellate courts by designation and was appointed by Reagan to the President’s Commission on Organized Crime.
Stewart suffered a stroke and died on December 7, 1985, at Dartmouth-Hitchcock Medical Center in Hanover, New Hampshire. He was seventy years old. He is buried at Arlington National Cemetery.