In early 2016, Justice Antonin Scalia died suddenly of a heart attack on a Texas ranch, sending his Supreme Court colleagues into a period of grief and uncertainty. Behind closed doors, they had to contend with another piece of unsettling news.

Justice Scalia, the leading light of the conservative legal movement, had left no plans for his working papers, according to five people aware of the situation. For a Supreme Court justice, this was the equivalent of dying without a will. With no instructions for creating an archive or opening it to the public, the definitive inside account of his work — and the court’s — could be lost or emerge with uncomfortable speed.

So following his death, his colleagues entered into private negotiations to try to head off any such situation in the future.

In a series of memos and conference meetings, Chief Justice John G. Roberts Jr. led the surviving justices in discussions about imposing a more uniform seal for their own papers, according to several people with knowledge of the process.

The absence of instructions from Justice Scalia and ensuing confidential conversations, which have not previously been reported, help explain why the nation’s highest court can be so difficult to understand. The ultimate record of the court’s work is considered the personal property of each justice, to dispose of or share as he or she chooses. And many of the justices have valued confidentiality over transparency and chosen to postpone scrutiny of their work for years to come.

In contrast with the executive branch, which is required to preserve and ultimately make public a record of its inner workings, there are no laws to determine what the justices save, shred, burn or reveal, or when. The court does not share any information about policies or plans for records; a spokeswoman for the court did not respond to written questions.

People familiar with the episode after Justice Scalia’s death, who spoke to The New York Times on the condition of anonymity because of the court’s sensitivity over disclosure of internal workings, recalled that a consensus was reached, but had differing memories of its terms and how solid or lasting it was.

Still, the death of Justice Ruth Bader Ginsburg, just a few years later, provides a clue: Her Supreme Court papers went, at her direction, to the Library of Congress on the condition that no case file would be opened until every justice involved in the matter had died, a restriction that could lock away many documents for decades.

Though some justices in previous eras arranged for their papers to be released not long after their own deaths, the trend on the Roberts court has been to impose much tighter restrictions, serving to further obscure a branch of government that has resisted calls for more transparency.

Each year, the justices carefully compose and edit about 60 opinions in argued cases to share with the world. The fuller, richer narratives of each case, showing the behind-the-scenes stories of how members of the court pressured, persuaded and prevailed over one another to arrive at those opinions, are hidden away in the justices’ working papers — their confidential internal memos and opinion drafts.

“There is a story behind every Supreme Court decision,” said Brad Snyder, a legal historian at Georgetown University and the author of a biography of Justice Felix Frankfurter. “Without the papers, we can’t understand it.”

The justices have said they want to keep those internal exchanges out of view, contending that secrecy protects the authority and finality of their decisions.

Since Justice Scalia’s death, two members of the court have retired. But neither of them, Justices Anthony M. Kennedy and Stephen G. Breyer, has announced plans for his papers.

Because of the court’s lack of transparency, it is impossible to say what will become of the inner history of its current work — which scholars say is more crucial, and more endangered, than ever.

In the decade since 2016, the Roberts court has been issuing many orders on what critics call the “shadow docket.” These temporary but consequential emergency rulings often lack routine information like tallies of how the justices voted or explanations of the court’s logic.

In those cases, the public will be able to learn the court’s reasoning only from the justices’ working papers, making the collections from the Roberts years particularly important. But if all of the current justices follow the same terms of Justice Ginsburg, that material will not emerge for generations.

And people familiar with the court’s operations say they worry that some of the most authoritative and revealing records are not being saved at all. That is because some work is now conducted digitally, via emails and texts. Those people, who spoke on the condition of anonymity to describe internal matters, said they were unaware of any consistent procedures for saving electronic records.

“We’ll be unable to write a rich history of the Roberts court,” Mr. Snyder said.

Many government agencies make clear to the public how the agency handles its records. But Patricia McCabe, a spokeswoman for the court, did not respond to questions about the court’s practices, including whether court emails are deleted.

Asked why the court refused to provide any information about its policies for document retention, Ms. McCabe declined to answer that question as well.

Surprises, Brawls and a Shredder

The revelations found in past justices’ working papers have been so potent that they have caused bruised feelings between the justices and blowups between government institutions.

And because no law governs the preservation of the justices’ work, each justice, assisted by staff, builds his or her own archival trove, deciding which memos, drafts, voting sheets and meeting notes to preserve.

Or destroy. In 1986, Justice Byron R. White, a former professional football player who staunchly guarded his privacy, summoned his clerks to his chambers for a special assignment that took several weekends. Together they marked his quarter-century on the court by feeding his records, including from the landmark Miranda rights case, into a shredder purchased for the occasion, according to Dennis J. Hutchinson, his biographer.

“Well, here’s an article. Here’s an entire book,” one of the clerks later told Mr. Hutchinson, describing what it was like to insert invaluable history into the jaws of the machine.

“I couldn’t believe how much history was going down the chute,” he said.

Two justices in modern memory opted for more open approaches. One spring morning in 1993, the justices opened their morning copies of The Washington Post to find detailed accounts of their internal debates. Earlier that year, Justice Thurgood Marshall, the first Black member of the court, had died, and his papers had been donated to the Library of Congress. With no announcement, the library had opened his papers for public review, and Post reporters had been digging through the newly released archive.

The surprise release led to a brawl over how to interpret the justice’s written instructions. In a furious public letter, Chief Justice William H. Rehnquist took a swing at the Library of Congress, accusing it of “bad judgment” and of opening the records, some only two years old, prematurely. Justice Marshall’s family sided with the chief justice, asking a senator to request that the papers be resealed. The library defended its reading of Justice Marshall’s instructions. The papers stayed open.

In the wake of that controversy, the justices considered establishing common timelines for releasing their papers but could not come to a consensus, according to the papers of Justice Harry A. Blackmun, who chose to make his papers public five years after his death.

“‘This is the people’s court, it’s not our court,’” Harold Hongju Koh, a Yale law professor and former Blackmun clerk, recalled his boss saying. “‘Who cares if we’re embarrassed. The main purpose here is to educate the public.’”

The 2004 release of Justice Blackmun’s papers again caused shock at the court, because of the unvarnished portrait they revealed. Unlike Justice Marshall, who had saved his papers haphazardly, Justice Blackmun had preserved his with pinpoint discipline.

The result was a 24-year chronicle of his time on the court that exposed tensions among the justices, his own heavy reliance on clerks and a bombshell: In 1992, the court had come close to overturning Roe v. Wade, but a centrist coalition of justices had secretly worked together to save the federal right to abortion. The precedent had been far more vulnerable than outsiders realized.

A year after that release, John Roberts joined the court as chief justice. The court’s new leader was reserved and disciplined. He rarely gave interviews or delivered speeches. His letters about the state of the federal judiciary, released annually over his 20-plus years as its head, have seemed designed to avoid making news. According to people who have worked at the court, his preference has been for the justices to speak in the official voice of majority opinions.

He disapproved of the release of the Blackmun papers, citing them from the bench during oral argument but calling them an “unfortunate” source of knowledge. After Justice Scalia’s death, the chief justice led the discussions among the justices about how to handle their papers, people familiar with the discussions said.

As for Justice Scalia’s own papers, his family directed that they be archived at Harvard Law School, which in 2017 announced that the case files would remain sealed until every other justice who participated in a case had died.

The most recent member of the court to die went even further. Justice David H. Souter, who retired in 2009 and died last year, left instructions that all of his papers remain sealed for 50 years. That means a complete record of Bush v. Gore, for instance, the court’s still-controversial decision to intervene in the 2000 presidential election, will not be available until 2075.

A Basement Trove

The fullest record of the Roberts court, meanwhile, is hidden away in its basement.

In the bowels of the Supreme Court, below the red-velvet grandeur of the courtroom and the shuffle of tourists, the justices are assigned storage rooms in which they store case files, said people familiar with the court’s practices.

Access to the records in the basement is highly restricted. But every year, about three dozen new people are allowed to read some of them: the justices’ incoming law clerks, who arrive for yearlong apprenticeships.

Reading those files clears away the mystery that surrounds the court, say those who have seen them. Clerks often ask to read the insider accounts of the most game-changing decisions, including how the justices decided to overturn limits on campaign spending in 2010 and approve gay marriage nationwide in 2015 — in both instances by just one vote.

But the deeper education, say those who have read the papers, is in learning about the dynamics among the justices. The papers reveal when a coalition has come together or dissolved, what has spurred the justices to sometimes cast surprising votes, the tactics they used to influence one another, and how they addressed one another in private.

In public remarks, the justices have argued that their judicial independence requires keeping these kinds of exchanges private, so they can bat around ideas and change positions.

If the justices “don’t have trust in one another and all the people who work for us, then those kinds of honest conversations that we need to do our business are not going to take place,” Justice Elena Kagan told senators earlier this summer while testifying on Capitol Hill about the court’s budget, as she decried reports in The Times and Politico that included internal information.

But some scholars question why papers should be sealed long after a justice has retired.

“It’s reputation management,” said Mary Ziegler, a legal historian at the University of California, Davis, adding that the justices are protecting themselves from examination and second-guessing.

The papers are “the most direct accountability mechanism” we have for justices, said Margaret Kwoka, a law professor at Ohio State University who studies government secrecy. She maintained that given the justices’ extraordinary, decades-long tenure, they should know their deliberations will be scrutinized within a reasonable amount of time.

The Presidential Records Act requires that White House records be preserved down to the last scrap, then made public five years after a president leaves office or, for some sensitive documents, 12 years. The Federal Records Act governs the retention of executive agency documents. There is no equivalent for the judiciary, and while the working papers of members of Congress are considered their personal property, some committee documents are preserved and released on a set schedule.

During the post-Watergate years, a congressional commission recommended converting judicial papers from private to public property and setting a uniform timeline for release, no more than 15 years after a justice leaves the bench. But legislators showed little appetite for adopting the idea, and the proposal was all but forgotten.

The Historians’ Worry

The Trump era has transformed and heightened the importance of the current justices’ working papers: Instead of merely revealing the back story of a lengthy published opinion, they will one day provide the public’s first opportunity to understand why the court ruled as it did in some emergency matters.

Since Mr. Trump’s return to office, the court has used its fast track, called the emergency or shadow docket, more than 20 times to allow his administration to implement contested policies. Some of those decisions have come without any legal reasoning.

“The more cases get decided without full opinions, the more important it is to get access to the papers,” Stuart Banner, a legal historian at the University of California, Los Angeles, said in an interview.

But it is virtually impossible to estimate when — if ever — the public might see those records.

The court’s liberals have criticized its opacity, and its newest member, Justice Ketanji Brown Jackson, has shown a willingness to buck her colleagues. She or another justice could unilaterally decide to reveal the court’s secrets at any time.

Provided they have been preserved. Scholars and historians are particularly worried about what electronic material is being saved at the court and how — another question the court has not answered.

“Even if no law applies to the Supreme Court’s records, their emails are still government property of great historical importance, which the court should manage and preserve for eventual public access,” said Gary M. Stern, a former general counsel of the National Archives.

And because each justice is his or her own boss, it is not clear that anyone is forcing them to confront or decide the issue — an uncomfortable one, because it is about their mortality.

Justice Breyer retired in 2022 and is now teaching at Harvard. He turned 88 in August.

In an email message, he did not respond to questions about the court’s practices. As for his own papers, he said, he is still considering his options.

Julie Tate contributed research. Ann E. Marimow and Adam Liptak contributed reporting.