Why Are Documents Classified?

By one historian’s account, the U.S. government classifies three documents every second. Assuming you’re not a speed reader, that means roughly 18 documents were labeled “classified” in the time it took you to read that first sentence. So why does the U.S. government want to keep so many documents secret from its citizens? And how did the practice become so common?

U.S. history is rife with examples of contentious debate over the release of documents prepared for and by the government. As early as 1774, the First Continental Congress decreed to “keep the proceedings secret, until the majority shall direct them to be made public.” But delays in making documents public often fuel public outcry. Those gaps are where conspiracy can grow and thrive decades after the fact, as evidenced by the Roswell UFO incident, the JFK assassination, and the September 11 attacks, to name just a few.

So perhaps it wasn’t surprising that in the summer of 2025 a yearslong investigation into multimillionaire sex offender Jeffrey Epstein dominated headlines when the administration of U.S. Pres. Donald Trump said it would not release the Epstein files, a reversal that angered many in Trump’s MAGA base and prompted bipartisan calls for transparency.

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Still, there are reasons—some good, some more dubious—that explain why the government is at times reluctant to release all the information it has about a given subject.

Some secrets should remain, well, secret

This is basically the “national security” argument. To state the obvious, information regarding how to build a nuclear weapon and where such weapons are kept is classified, and most people probably are fine with that. There are some situations where the benefit of revealing information outweighs the potential damage such a revelation could bring. Often “sources and methods” are considered classified. Those are the people and operational details used to carry out military strikes or intelligence operations. Sources can be on-the-ground operatives, including CIA agents or foreign nationals assisting with cover operations. Revealing their names, or even vague details about them, could compromise their safety. This protection of sources can continue even after death. The CIA Memorial Wall at the agency’s Virginia headquarters honors the 140 CIA officers killed in the line of duty, but the names of 32 of them remain classified. An example of classified “methods” is Secret Service strategies for protecting the president or other high-profile government officials.

Sometimes there are time limits, often 25 years, that are put on the release of information. What is seen as a national security threat in one decade can be viewed very differently years later (keep reading for an example of that involving the Pentagon Papers). But even documents that have reached their “expiration date” still need to be reviewed by human beings to make sure that other aspects of the documents don’t pose threats. A 2010 government report put the backlog of pages needing to be read that were 25 years or older at 400 million.

Finally, presidents have broad discretion about what can and should be declassified. For example, while details on how to build and store a nuclear weapon will probably never be made public, the number of nuclear weapons in the U.S. stockpile was declassified in 2010 by Pres. Barack Obama.

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Some secrets are, well, embarrassing

Sometimes the government cites “national security” concerns or other reasons for not declassifying documents when the reality is that making some of these documents public could cause appreciable embarrassment, sometimes to both the government—for acting badly—and the subjects, also for acting badly. Examples include:

• Medical experiments: In 1945 the U.S. government began a series of experiments on people, without their consent, to assess the effects of radiation on the human body. Several years later, after revelations of Nazi atrocities led to the establishment of new guidelines for ethical medical research, those responsible for the radiation experiments had the work classified so that their own unethical experiments would not be uncovered. A Department of Energy inquiry in the 1990s uncovered the details of the program, which went on for some 30 years.

• MLK surveillance: J. Edgar Hoover’s FBI spied secretly on Martin Luther King, Jr. With the permission of Attorney General Robert F. Kennedy, listening devices were placed in the homes, offices, and hotel rooms of King and his associates. This was part of a broader FBI initiative named COINTELPRO, in which the FBI sought information on groups it saw as being disruptive to society. Those groups ranged from the Black Panthers to the Ku Klux Klan. But it included a particular focus on King, whom Hoover suspected of being a communist. The FBI gathered information about King’s extramarital affairs and subsequently sent King an anonymous letter describing proof of adultery and seemingly pressuring him to kill himself to avoid public disclosure. Classified documents related to the COINTELPRO operation were stolen in the early 1970s by an activist group and leaked to the news media. Subsequently, they were the subject of investigation by the Church Committee, a Senate probe into alleged abusive practices by the CIA, FBI, and other parts of the government.
• The Pentagon Papers: These documents tell the story of the U.S. role in Indochina from World War II to May 1968 and were commissioned in 1967 by U.S. Secretary of Defense Robert S. McNamara. They were leaked to The New York Times by researcher Daniel Ellsberg in 1971. When the Times, and subsequently The Washington Post, began publishing the contents of the roughly 3,000-page classified document later that year, the Department of Justice got a restraining order to stop publication based on the “immediate and irreparable harm” to U.S. military interests that further publication would do. The fight went to the U.S. Supreme Court, and, in a landmark ruling for freedom of the press, the Court cleared the way for the publication of the documents. In 1989 Erwin N. Griswold, who argued the government’s case before the Supreme Court in 1971, wrote an op-ed in The Washington Post, saying that the Pentagon Papers represented “massive overclassification and that the principal concern of the classifiers is not with national security, but rather with governmental embarrassment of one sort or another.”

Some secrets aren’t worth telling

Have you heard the phrase “garbage in, garbage out”? It argues that the quality of the input affects the quality of the output. The same can be said for government investigations. Another way to think about it is “consider the source.” People who undertake investigations may be seeking the truth—or they may have other underlying motivations. The same can be said for those who are asked to testify in investigations: they may be trying to protect their interests (and prevent embarrassment, see above); they may be trying to exact revenge; they may have other motivations. Part of the role of an investigation is to determine what is verifiable information and what is salacious gossip. For example, the public may have a real interest (and right) to know the names of public officials linked to known criminals. But if those connections aren’t corroborated, irreparable harm could be done.

Such consideration was lacking during the 1940s and ’50s when the House Un-American Activities Committee and Sen. Joseph McCarthy were feeding off post World War II fears of the Soviet Union and creating “blacklists” of suspected communists. In 1947 the Hollywood Ten, a group of screenwriters, were called to testify before Congress and asked if they were communists. When they refused to answer, they were charged with contempt of Congress and jailed. Hollywood film executives agreed not to hire any of the group or anyone else suspected of being a communist. The impact went far beyond the 10 individuals as other writers left the United States or wrote under pseudonyms for fear of experiencing similar fates.

In 1950 McCarthy made an appearance before a group of Republican women in West Virginia and told them that the State Department was “thoroughly infested with communists.” He said he had a list that contained the names of 57 such individuals. The list was, in fact, an odd amalgam of numbers, memories, and other less-than-reliable data, but its impact was to create a deep paranoia in the country. That paranoia, one historian estimates, cost tens of thousands of people their jobs.

Imagine a world in which the investigation into communists in the United States had been classified and the documents naming those interviewed had never been unclassified because the evidence wasn’t solid enough for their names to become public, and you begin to understand the fine line between full disclosure and undue secrecy. That is at the center of the Epstein files debate. The names of some very prominent people are known to appear in parts of the files that have been made public—including former president Bill Clinton, Prince Andrew, Michael Jackson, and Trump. Is there a public interest in knowing if world leaders were part of a sex-trafficking organization? Is being named in a document synonymous with guilt? How should those competing interests be weighed? (In documents already released, there is no accusation of wrongdoing by Clinton, Jackson, or Trump. Prince Andrew has denied any wrongdoing.)

Other forms of harm involve those affected. Even those arguing for the release of the Epstein files concede that there is a need to protect the names and likenesses of victims as well as any illegal content that depicts minors and victims.

The case for sharing secrets

While most of the time the discussion of classified documents involves how to keep them secret and the laborious processes undertaken to declassify them, the reality is that presidents can—when they choose to—act with great alacrity. But the decision to declassify documents can be as complicated—and fraught with uncertainty around the outcome—as the classification itself.

In the months leading up to the Russian invasion of Ukraine, Pres. Joe Biden’s administration shared highly classified information about the Russian military buildup with European allies. The move was controversial both because it largely broke with precedent in sharing military intelligence with other countries and because politically it could be seen as warmongering instead of peacemaking. Ultimately, classified and other intelligence information was shared with European allies in a bid to solidify Western opposition to Moscow. While it definitely got the attention of the world, it did nothing to stop the war.

On October 16, 1962, Pres. John F. Kennedy received incontrovertible photographic evidence taken from U-2 spy planes that the Soviets had installed missiles in Cuba. Kennedy addressed the country about the crisis, and on October 25 the U.S. ambassador to the UN displayed the photographs to the world. Within days the Soviets agreed to remove the missiles.

A less successful UN presentation of classified information occurred in 2003, in the run-up to the Iraq War. In February 2003 U.S. Secretary of State Colin Powell spoke to the UN Security Council about Iraq’s weapons of mass destruction, a phrase he used 17 times in the hour-long address. He told members of the security council:

My colleagues, every statement I make today is backed up by sources—solid sources.

Those sources included tape recordings, aerial photography, and maps that were subsequently proved to be infamously unreliable.