President Joseph R. Biden, Jr. and his Supreme Court nominee Ketanji Brown Jackson and Vice President Kamala Harris just before the investiture ceremony for Jackson on September 30, 2022, in Washington, DC. Supreme Court of the United States via Getty Images

To emphasize the importance of an election, presidential candidates often predict that the next president will have an opportunity to fill one or two vacancies on the U.S. Supreme Court.

However, this may not be true in the case of a hypothetical President Kamala Harris. Even if Harris were to win in November 2024 and then win reelection in 2028, she may not have a chance to reshape the court by filling the seat of a departing justice, especially a conservative one.

Jimmy Carter was the only one-term president who didnโ€™t fill a Supreme Court vacancy. No president who won reelection has been denied this opportunity. In contrast, President Donald Trump was able to appoint three justices in a single term.

This inconsistency is one of the reasons why President Joe Bidenโ€™s call for Supreme Court reform, which Vice President Harris supports, should be considered a meaningful attempt to address a relatively new development that has diminished the people’s abilityโ€”through their elected representatives in the White House and the Senateโ€”to shape an unelected Supreme Court.

Bidenโ€™s reform plan, outlined in an op-ed and a speech at the LBJ Presidential Library in Austin, Texas, includes two major legislative elements: 18-year term limits for justices and a โ€œbinding code of conductโ€ for the courtโ€™s members. The former proposal is particularly relevant for the future makeup of the court and the presidential election in November.

Watch as President Biden call for Supreme Court reforms as he delivers remarks on the 60th Anniversary of the Civil Rights Act

The Supreme Courtโ€™s place in American democracy

While every child in America learns in school about the Supreme Courtโ€™s independence, historically, the justices have not been walled off from the larger world, issuing decisions while wearing political blinders.

Instead, they have been aligned with the enduring political regimes that dominated much of American history. Consider, for example, Thomas Jeffersonโ€™s Democratic-Republican Party and Abraham Lincolnโ€™s Republican Party. Each party won six presidential elections in a row. Franklin D. Rooseveltโ€™s Democratic Party won five straight presidential elections. From 1968-1992, Republicans won five of six presidential elections.

The courtโ€™s alignment with a dominant regime mattered greatly for American democracy. It was the primary reason political scientist Robert McCloskey concluded in his widely read book, โ€œThe American Supreme Court,โ€ first published in 1960, that the justices rarely โ€œlagged far behind nor forged far ahead of America.โ€ Instead, McCloskey concluded, the court had typically stayed in line โ€œwith the mainstreams of American life and seldom overestimated its own power resources.โ€

A great deal has changed in the six-plus decades since McCloskey wrote those words. As I argue in my recently published book, โ€œA Supreme Court Unlike Any Other: The Deepening Divide Between the Justices and the People,โ€ those changes have undermined the courtโ€™s democratic legitimacy because the electoral link that once existed doesnโ€™t anymore. Democratic candidates have won the popular vote in seven of the past eight presidential elections. Yet, six of the nine current justices have been appointed by Republican presidents.

One of the key changes has been the length of time justices serve today. Consider that when Chief Justice John Marshall died in 1835, he set a record for service โ€“ at 34 years and five months โ€“ that would only be surpassed by one justice over the next 140 years. Indeed, from 1789 to 1971, justices served just over 16 years on average.

Today, however, presidents of both parties choose young nominees โ€“ generally around 50 โ€“ with the expectation that they will serve several decades. As I write in my book, โ€œif the justices of today stay on their current course, Marshallโ€™s mark will become commonplace. Assuming all stay on the Court until their eighty-fifth birthday โ€“ a few months older than the mean age of the last five justices to depart โ€“ they will have served thirty-three years on average.โ€

A group of people, most of whom are wearing black robes, stand shoulder to shoulder in a formal looking room with a carpet and wood panels on the walls.
The Supreme Court justices pose with President Joe Biden and Vice President Kamala Harris in Washington in September 2022, on the day Ketanji Brown Jackson joined the court. Collection of the Supreme Court of the United States via Getty Images

No change for another decade?

Consider that soon after he won his brutal confirmation fight in 1991 at the young age of 43, Clarence Thomas pledged to serve until he was 86. While those words were spoken long ago and may not be fulfilled, they highlight a central concern about the courtโ€™s place in American democracy today.

To help explain, letโ€™s take Thomas at his word and assume for a moment that heโ€™s able and, indeed, does fulfill that promise he made long ago.

That would mean that at 76, Thomasโ€”currently the oldest justiceโ€”would stay on the court for another decade. As noted above, this is not a wild assumption, as justices routinely stay on the court well into their 80s. Recall that Ruth Bader Ginsburgย was 87 when she died in 2020, and John Paul Stevens was 90 when he retired in 2010.

Letโ€™s further assume that none of the other eight younger justices die or retire before Thomas. That would mean there would not be another Supreme Court vacancy until 2034 when Thomas departs after 43 years โ€“ nearly seven years longer than the current record held by William O. Douglas.

It would also mean that if Harris were elected to the presidency in November and reelected in 2028, she would not have an opportunity to alter the court.

The court and political change

Enabling change is a centerpiece of democracy. However, in choosing like-minded youthful nominees intended to serve for decades, presidents hope to insulate policy from the ballot box.

Presidents admit as much by often saying that one of the most significant decisions they make in the Oval Office is their selections for the Supreme Court.

Why? Itโ€™s because those presidents understand that the justices will continue to affect American law and politics long after their presidencies have come to an end and long after the elections they won have faded from our collective memories.

For much of American history, justices served an average of approximately ten and a half decades. However, only one justice appointed in the last fifty yearsโ€”David Souterโ€”has served less than two decades.

So, while the rules of lifetime service have always been in place, the justices of today have altered the terms of the arrangement. It used to be rare for a justice to serve for three decades. Now, itโ€™s expected.

Bidenโ€™s reform

Bidenโ€™s call for an 18-year term limit for the justices seeks to rectify this development, putting the court back in its historical routine.

With two vacancies every two years, voters will understand the potential impact of their presidential vote on the makeup of the court. They would know the forthcoming departures and should be informed of the types of high court appointees the presidential candidates have promised to choose.

Finally, voters will no longer have to morbidly sit back and wonder if an aging justice will live past the next election, as liberal voters did with Ginsburg in 2020. The result will be a court more in line with the democratic traditions of the nation.

Given the lame-duck status of the president and Republican control of the House, the term-limit proposal will not pass this year. Nevertheless, it offers voters something serious to consider as they make their decisions about the candidates.

And, as a scholar who studies the American presidency and the Supreme Court, I believe it offers an opportunity to provide the court with a greater sense of democratic legitimacy.

Kevin J. McMahon is a professor of political science at Trinity College

This article has been republished with permission from The Conversation.