This article is part of a special report on the 50th anniversary of the Pentagon Papers.

One night during the legal battle over the Pentagon Papers, Max Frankel was stewing with anger. Mr. Frankel, then the Washington bureau chief of The New York Times, remembered that he was the only one at the table during the newspaper’s deliberations with its legal team who had actually read the papers. Yet he was stunned when the outside lawyers hired by the newspaper to defend it asserted that the journalists had somehow erred by publishing national secrets.

“So I dashed off a long memo to make them understand how Washington works,” Mr. Frankel, who went on to become the paper’s executive editor from 1986 to 1994, recalled last month. The memo offered a ground-truth guide to the realities of government, journalism and secrecy in the nation’s capital. The lawyers were impressed and decided that the judges hearing the dispute could use a similar lesson, so they turned Mr. Frankel’s memo into an affidavit and submitted it along with the briefs in the case. What resulted was a legal document unlike any other. A close reading shows how much such trading in secrets still drives Washington today.

In his affidavit, Mr. Frankel peeled back the fiction of a government dependent on secrets, valiantly guarding them against unscrupulous journalists, instead explaining the more intricate relationship in which all sides are involved in the information trade. And in the process, he exposed the false outrage of government officials who protest the disclosure of sensitive details when they themselves regularly traffic in them for their own purposes. In that, not much has changed. Hypocrisy is one commodity of which there remains no shortage in the capital.

Fifty years later, this is still an apt description of how Washington works. “Secrets,” as the government describes them, are the coin of the realm. Public officials and journalists deal in them constantly, and aggressive reporting by news outlets is as critical as ever in keeping the public informed about how the government is wielding power in its name.

In a few pithy sentences, Mr. Frankel made the point that in Washington everyone leaked secrets and for a variety of reasons, many of them less than altruistic. The same bureaucratic rivalries and political imperatives that applied in 1971 apply today. Presidents are still wooing electorates; the armed forces are still in competition for budgetary dollars; and officials still seek to gain support, sabotage opponents or lobby against their superiors — all through strategic leaks.

Mr. Frankel’s Washington was a cozier one than today’s, one where presidents routinely hobnobbed with select journalists and spoke with them without their words’ being attributed to them. While presidents these days sometimes directly spin reporters without their names attached, they usually leave the more serious leaking to others. I’ve covered the last five presidents, and none of them ever stood next to me in a swimming pool, as President Lyndon B. Johnson had done with Mr. Frankel, to give a rundown of the latest conversation with a Russian leader.

President Donald J. Trump was an occasional exception. Chris Christie, the former governor of New Jersey, discovered that in 2018, when Jonathan Swan of Axios reported that Mr. Trump was considering Mr. Christie for White House chief of staff. When Mr. Christie expressed concern about the leak, the president told him, “Oh, I did it,” according to “A Very Stable Genius” by Philip Rucker and Carol Leonnig. According to the book, Mr. Christie was shocked and thought: “You’re leaking yourself? And to think I came this close to being your chief of staff.”

Obtaining direct notes of a president’s meeting with another foreign leader is pretty rare today, but transcripts of two of Mr. Trump’s early conversations with the president of Mexico and the prime minister of Australia were leaked in 2017 to The Washington Post, which posted them online. Unlike Mr. Frankel’s example, the revelation here was presumably not authorized by Mr. Trump but disclosed by people who were alarmed by the conversations.

The episode led an angry president to become so guarded about future leaks that after one of his talks with President Vladimir V. Putin of Russia, Mr. Trump demanded that the interpreter hand over notes of the discussion. Mr. Trump did authorize the disclosure of one of his conversations with a foreign leader, the July 2019 telephone call in which he pressured Ukraine’s president to “do us a favor” and investigate former Vice President Joseph R. Biden Jr. and other Democrats. But Mr. Trump released it openly, not through a leak, in hopes of proving he did nothing wrong. House Democrats were not convinced and impeached him anyway.

Dean Rusk was neither the first nor the last senior Washington official to deliver a message to a reporter under the cloak of anonymity that was diametrically the opposite of what he said when the cameras were on. In one memorable example, a spokesman for President George W. Bush’s Coalition Provisional Authority in Iraq summed up the disastrous progress of the war in 2004 to Rajiv Chandrasekaran of The Washington Post: “Off the record: Paris is burning. On the record: Security and stability are returning to Iraq.” During the beginning of the coronavirus pandemic last year, Mr. Trump similarly told Bob Woodward that it was “deadly stuff” and in fact “more deadly” than the ordinary flu, while at the same time telling the public that it was “a little like the regular flu” and would disappear.

The government makes no spousal exception to its rules on secrets, but that does not stop some officials from filling in their partners. When the Obama administration was about to launch its raid to capture or kill Osama bin Laden, Hillary Clinton, then secretary of state, did not even tell her husband, Bill, the former president, who has pretty high clearance. But Bill Daley, then the White House chief of staff, was not so discreet. He revealed to Garrett Graff, in an oral history published by Politico Magazine in April, that when his wife asked why he was so preoccupied, “I took her down to the first-floor bathroom, turned on the faucet, took her in the shower, shut the shower door and whispered in her ear: ‘We’re going to go after Osama bin Laden.’”

Even in an era of gushing leaks, one area that remains taboo for journalists is reporting information that would clearly put American troops at immediate risk. When a few other reporters and I were embedded with the Marine general commanding the drive toward Baghdad in 2003, we were privy to information about future military plans, but never published it until after any operations had taken place. But sometimes the government insists on protecting troop movements even long after the fact; our former New York Times colleague Tim Weiner disclosed one such absurdity while at The Baltimore Sun in 1991 when he found that among the files still classified was one on World War I troop movements in 1917.

Government officials these days are even more addicted to classifying information than they were in Mr. Frankel’s day, no matter how routine or unremarkable the details may be. There is no perceived cost to overclassifying, whereas officials who fail to mark documents “confidential,” “secret” or “top secret” take a risk of being accused of being too cavalier with sensitive information. In 2016, the last year a full accounting was made, the government reported 39,240 classification decisions.

“Everyone who has looked at the issue agrees that the government classifies too much information for too long,” said Steven Aftergood, director of the Project on Government Secrecy at the Federation of American Scientists. “It is the path of least resistance.” Even some of those who oversee agencies that rely on secrets think it has gone too far. Last year, Gen. John Hyten, vice chairman of the Joint Chiefs of Staff, told an audience, “In many cases in the department, we’re just so over-classified it’s ridiculous, just unbelievably ridiculous.”

Journalists are less deferential today to arguments that revealing sensitive information will affect alliances, but editors before publication regularly hear out government officials maintaining that disclosures would harm national security in some way. In some cases, they make a persuasive case, and The New York Times and other publications have withheld particular pieces of information. When WikiLeaks obtained reams of State Department cables and provided them to The Times, the paper did not publish the names of Afghan informers who might be subject to retaliation if their cooperation with American authorities were known. But most of the time, when officials seek to persuade editors not to go forward, what they are trying to avoid is not damage to national security but personal embarrassment or political trouble, neither of which is a news organization’s job to guard against.

If anything, memoirs are even more common today than they were in Mr. Frankel’s time. Dozens of presidential aides and appointees end up writing books about their time in government, often recounting episodes and conversations behind closed doors in great detail. Many of them have to go through a review process whereby the government scours the manuscript for classified information, but the interpretation is often quite subjective and even political.

When John R. Bolton, the former national security adviser, submitted a memoir in which he was highly critical of Mr. Trump, a career official said he could not directly quote the president. He left in the words attributed to the president, but simply deleted the quotation marks. The book was then cleared for publication. Only later did a Trump appointee with no experience in classification overrule the career official and declare that the book actually did contain secrets. Mr. Bolton considered it nothing more than a blatant effort to stifle a critical account of the president and published anyway. He is now in court defending against a Justice Department lawsuit.

Now as then, many of the fights journalists get into with the government over secrets concern not current-day events but episodes that took place in the past. In other words, what is at stake is less the continuing security of the country than the reputations of the people who once ran it. The New York Times and its reporters have filed 81 federal lawsuits under the Freedom of Information Act since 2003, some of them seeking documents about actions and decisions made under presidents who have already left office, trying to discern, as Mr. Frankel wrote, “the thoughts, debates and calculations of the decision-maker.”