For most people, moonlighting means delivering pizzas, driving for a rideshare service, or discovering that the phrase “flexible part-time hours” was composed by someone with an unusually creative understanding of both “flexible” and “part-time.”

Supreme Court justices generally do not need to supplement their income by working the evening shift. As of 2026, an Associate Justice of the U.S. Supreme Court receives an annual salary of $306,600, while the Chief Justice receives $320,700. More importantly, a seat on the nation’s highest court would seem to provide about as much professional prestige as one human being could reasonably require.

And yet, history has repeatedly demonstrated that “reasonably require” is not necessarily a phrase one should use when discussing highly ambitious people in Washington.

Since the Supreme Court began operating in 1790, only 116 people have served as justices. Among that small group are men who ran for governor while still hearing cases, flirted with the presidency or vice presidency, temporarily left judicial work to prosecute Nazis, investigated Pearl Harbor, chaired the Warren Commission, and otherwise demonstrated that a lifetime appointment to the Supreme Court was not always enough to keep the résumé from growing.

Not all of these were literally “side jobs.” Some justices pursued other positions while remaining on the Court; others resigned, wandered through politics or diplomacy, and occasionally came back. Taken together, however, they make it clear that the supposed wall separating the Supreme Court from the rest of political life has historically had a surprising number of doors.

John Jay Ran for Governor While Serving as Chief Justice

John Jay had already accumulated enough accomplishments for several respectable biographies before George Washington nominated him as the first Chief Justice of the United States in 1789. He had served in the Continental Congress, worked as a diplomat in Spain, helped negotiate the Treaty of Paris ending the Revolutionary War, served as Secretary of Foreign Affairs, and contributed five essays to The Federalist Papers.

In other words, Jay was not suffering from a shortage of things to put on LinkedIn.

Nevertheless, while serving as Chief Justice, he permitted himself to be nominated for governor of New York in 1792. Jay lost that contest to George Clinton amid disputed ballots and considerable political unpleasantness, which at least proves that election controversies did not need cable television in order to flourish.

Three years later, Jay tried again. This time he won. According to the Supreme Court Historical Society, he resigned from the Court on June 29, 1795, and became governor of New York.

Jay’s willingness to participate openly in partisan politics while sitting as Chief Justice may look startling today, but the early Supreme Court existed in a political culture very different from the modern judiciary. The boundaries between judicial, diplomatic, and political activity were considerably fuzzier. The Founders were, after all, inventing the federal government as they went along, which is one reason debates over what kind of government they actually created continue to keep historians and internet comment sections gainfully occupied. We looked at that broader question in our article “Is the United States a Democracy? Why the Founders Built a Republic on Purpose.”

Smith Thompson Tried the Governor Route, Too

Justice Smith Thompson apparently looked at John Jay’s résumé and decided the governor-while-justice arrangement deserved another try.

Thompson had already served as chief justice of New York’s highest court and as Secretary of the Navy before President James Monroe placed him on the U.S. Supreme Court in 1823. According to the Supreme Court Historical Society, Thompson had actually considered running for president in 1824 before abandoning the idea and accepting his Supreme Court position.

Four years later, the political itch returned.

While still serving as a justice, Thompson ran for governor of New York in 1828. He lost. Having tested both the presidential and gubernatorial waters, Thompson finally accepted the grim fate that had befallen him: he would have to content himself with being merely a Justice of the United States Supreme Court.

He remained there until his death in 1843.

David Davis Nearly Got to Decide Who Became President

David Davis was a close political ally of Abraham Lincoln and played a major role in Lincoln’s successful 1860 presidential campaign. Lincoln rewarded him by appointing him to the Supreme Court in 1862.

Davis, however, had political ambitions of his own. His name circulated as a possible presidential candidate during the 1872 election, and in 1877 he left the Court after being elected to the U.S. Senate from Illinois.

His timing was extraordinary.

The disputed presidential election of 1876 between Rutherford B. Hayes and Samuel J. Tilden had produced competing electoral returns from several states. Congress created a special Electoral Commission to determine which returns should count. The commission was designed to include five Supreme Court justices, and the other four initially selected Davis as the fifth—the supposedly independent member who could break the partisan deadlock.

Then the Illinois legislature elected Davis to the Senate.

Davis declined to serve on the Electoral Commission, leaving Justice Joseph P. Bradley to take his place. Bradley ultimately sided with the commission’s Republicans, helping award the disputed electoral votes to Hayes and giving him the presidency by a single electoral vote. The Supreme Court Historical Society provides a detailed account of the extraordinary episode.

Davis therefore managed the unusual accomplishment of leaving the Supreme Court for another job at precisely the moment when staying put might have made him one of the most consequential individual voters in American political history.

The full story contains even more twists, including Davis later becoming president pro tempore of the Senate. We gave his remarkable career its own article: “The Man Who Almost Single-Handedly Decided a Presidential Election.”

Charles Evans Hughes Left the Court to Run for President — Then Came Back as Chief Justice

If the previous examples suggest that Supreme Court justices occasionally suffered from political restlessness, Charles Evans Hughes turned restlessness into a full-scale career plan.

Hughes was governor of New York when President William Howard Taft nominated him to the Supreme Court in 1910. He served as an Associate Justice for six years before the Republican Party decided that what it really needed in 1916 was a presidential nominee with recent Supreme Court experience and an exceptionally formidable beard.

Hughes resigned from the Court and ran against President Woodrow Wilson.

The election was extremely close. Early returns made a Hughes victory look so likely that the Republican nominee reportedly went to bed believing he had won. By morning, the situation had deteriorated considerably. Wilson carried California by fewer than 4,000 votes and secured reelection. We previously examined Hughes’ exceptionally brief period of being the presumed next president in “A Short-Lived and Premature Celebration.”

That defeat did not exactly send Hughes into retirement.

He returned to law practice, then served as Secretary of State under Presidents Warren G. Harding and Calvin Coolidge. He later became a judge of the Permanent Court of International Justice at The Hague.

Then came the remarkable part.

In 1930, President Herbert Hoover nominated Hughes to return to the U.S. Supreme Court—not as an Associate Justice, but as Chief Justice. As the Supreme Court’s own historical account notes, Hughes succeeded William Howard Taft, the very president who had first appointed him to the Court twenty years earlier.

Hughes served as Chief Justice until 1941. His career thus included governor, Supreme Court justice, presidential nominee, Secretary of State, international judge, and Chief Justice.

Some people collect stamps.

William O. Douglas Almost Became Franklin Roosevelt’s Running Mate

William O. Douglas joined the Supreme Court in 1939 at age 40 and ultimately served for more than 36 years, still the longest tenure of any justice in the Court’s history.

That record almost never happened.

In 1944, President Franklin D. Roosevelt was preparing to seek an unprecedented fourth term, but Democratic leaders wanted to replace Vice President Henry Wallace on the ticket. Among the serious possibilities were Missouri Senator Harry Truman and Justice William O. Douglas.

Roosevelt sent Democratic chairman Robert Hannegan a letter indicating that he would be happy to run with either Truman or Douglas. Truman ultimately got the nomination.

That decision was rather consequential.

Roosevelt died less than three months after beginning his fourth term, making Truman president. Had Douglas received the vice-presidential nomination and the Roosevelt-Douglas ticket won—as Roosevelt and Truman did—Justice Douglas would have moved from the Supreme Court to the White House in April 1945.

Douglas remained politically interesting even after that near miss. Oral-history material preserved by the Harry S. Truman Presidential Library records discussions of Douglas as a vice-presidential possibility again in 1948.

Instead, he stayed where he was and continued serving on the Supreme Court until 1975. Sometimes the most historically important career move is the one you do not make.

Arthur Goldberg Gave Up a Lifetime Appointment for the United Nations

Arthur Goldberg’s story involves one of the more curious voluntary departures from the Supreme Court.

President John F. Kennedy appointed Goldberg to the Court in 1962. Three years later, President Lyndon B. Johnson persuaded him to resign his lifetime judicial appointment and become the U.S. ambassador to the United Nations following the death of Adlai Stevenson.

Goldberg accepted partly because he believed the diplomatic position would give him greater influence over American policy in Vietnam. That expectation did not work out quite as planned.

The Supreme Court Historical Society notes that Goldberg left the Court in July 1965 after just three years of service. He remained at the United Nations until 1968, becoming increasingly frustrated with the Vietnam War, and then returned to private law practice.

Giving up a lifetime appointment to the Supreme Court is an unusually large wager on a career change. Goldberg later made little secret of the fact that he sometimes wished events had unfolded differently.

Robert Jackson Took Time Off From the Supreme Court to Prosecute Nazis

Robert H. Jackson provides perhaps the strongest argument that the phrase “Supreme Court side job” can occasionally involve stakes somewhat higher than the typical weekend gig.

Jackson had served as Solicitor General and Attorney General before Franklin D. Roosevelt appointed him to the Supreme Court in 1941. Four years later, while still a sitting justice, President Harry Truman selected him for an extraordinary assignment.

Jackson became the chief U.S. prosecutor at the Nuremberg Trials.

According to the Robert H. Jackson Center, Truman appointed Jackson in May 1945 to lead the American prosecution of major Nazi war criminals. Jackson helped shape the legal framework for the trials and delivered opening and closing arguments that became landmarks in the development of international criminal law.

This was not a resignation from the Court. Jackson remained a Supreme Court justice while spending much of 1945 and 1946 working on the prosecution in Europe.

When the Nuremberg proceedings concluded, he returned to regular Supreme Court duties and remained on the bench until his death in 1954.

Most people returning from a temporary assignment bring back a coffee mug and several hundred unread emails. Jackson returned from helping establish principles governing crimes against humanity.

Owen Roberts Investigated Pearl Harbor While Serving on the Court

Justice Owen J. Roberts received his own major extracurricular assignment after one of the darkest days in American history.

President Herbert Hoover appointed Roberts to the Supreme Court in 1930. Before joining the Court, Roberts had practiced law in Philadelphia and had served as a special federal prosecutor investigating corruption connected with the Harding administration, including the Teapot Dome scandal.

After Japan attacked Pearl Harbor on December 7, 1941, President Franklin D. Roosevelt created a commission to investigate what had gone wrong and placed Roberts in charge.

The Supreme Court Historical Society notes that Roberts oversaw the Pearl Harbor investigation while still serving on the Court. He later headed another wartime commission concerned with cultural property and artwork seized during the war.

The first Roberts Commission examined the military and governmental failures surrounding the surprise attack and issued its report in January 1942. Its conclusions became controversial, particularly its criticism of senior commanders in Hawaii, but Roberts had nevertheless spent weeks simultaneously occupying the roles of Supreme Court justice and presidential investigator.

For more on just how many warning signs preceded the attack, see our examination of the missed Pearl Harbor warnings and intelligence failures.

Earl Warren Chaired the Warren Commission While Serving as Chief Justice

Earl Warren had already enjoyed a substantial political career before arriving at the Supreme Court. He served as attorney general and governor of California, became the Republican Party’s vice-presidential nominee in 1948, and sought the Republican presidential nomination in 1952.

Dwight D. Eisenhower instead won the nomination and the presidency. The following year, after the death of Chief Justice Fred Vinson, Eisenhower nominated Warren to lead the Supreme Court.

A decade later, Warren received an assignment that ensured his name would become attached permanently to one of the most studied and debated events in American history.

Following the assassination of President John F. Kennedy on November 22, 1963, President Lyndon B. Johnson created the President’s Commission on the Assassination of President Kennedy and appointed Warren as its chairman.

The commission spent months reviewing testimony, documents, forensic evidence, and the circumstances surrounding both Kennedy’s murder and the subsequent killing of Lee Harvey Oswald. Its final report concluded that Oswald acted alone in assassinating Kennedy and that Jack Ruby acted alone in killing Oswald.

The National Archives preserves the Warren Commission report and supporting records, which have continued to attract researchers, historians, critics, and conspiracy theorists with enough material to remain occupied indefinitely.

Warren, meanwhile, continued serving as Chief Justice until 1969.

The Kennedy assassination has generated an astonishing number of historical side stories. One of the strangest involves photographer Jacques Lowe’s archive of approximately 40,000 Kennedy negatives, which survived for decades only to be destroyed in the World Trade Center on September 11, 2001.

Supreme Court Justices Have Not Always Stayed in Their Lane

The modern image of a Supreme Court justice is one of deliberate separation from ordinary political life. Justices receive lifetime appointments, rarely run for public office, and generally cultivate the impression that the judicial branch exists at some dignified distance from elections, campaigns, diplomatic negotiations, criminal prosecutions, and presidential commissions.

History is less tidy.

John Jay ran for governor while Chief Justice. Smith Thompson did the same as an Associate Justice. David Davis left the Court for the Senate just as Congress was preparing to hand him a potentially decisive role in the election of a president. Charles Evans Hughes resigned to run for president and later returned as Chief Justice. William O. Douglas came remarkably close to joining a presidential ticket. Robert Jackson prosecuted Nazi war criminals while remaining a sitting justice. Owen Roberts investigated Pearl Harbor. Earl Warren investigated the assassination of a president.

The Supreme Court may be the nation’s highest court, but its members have never existed entirely outside the political and historical world around them.

Some of them, in fact, appeared determined to experience as much of that world as possible before anyone could tell them to pick one career and stick with it.

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