When the late Robert S. McNamara, secretary of defense for presidents John F. Kennedy and Lyndon B. Johnson, commissioned a group of “defense intellectuals” in the late 1960s to create a sober, thoughtful study of the evolution of one of America’s worst foreign policy blunders, the Pentagon Papers—forty-seven volumes, in all their greyness—were intended as good reading, perhaps, in the 1990s or later. What the country got instead, beginning on June 13, 1971, just as President Richard M. Nixon’s paranoia was building, was the sudden release of most of this material in The New York Times, then The Washington Post and elsewhere, revealing a sorry bipartisan history of lies and deception. This resulted in an epic court battle between the government and the press and, beginning a year later, the wild and unpredictable criminal trial—under the Espionage Act, among other statutes—of the main protagonist, former Pentagon official Daniel Ellsberg, who had leaked the Papers.

The Nixon administration was caught unawares by the revelations in the Papers, and went on an unseemly chase to figure out what the documents were, where they had come from, and how to control the presumed damage from their release. The panic was particularly poignant at the time because then-Secretary of State Henry A. Kissinger was engaged in secret negotiations to open a relationship between the United States and the People’s Republic of China; he feared that Mao Zedong and Chou En-lai would suspend talks with a government that couldn’t keep delicate matters confidential. He persuaded Nixon and his attorney general, John N. Mitchell, to go to court against the newspapers and seek a prior restraint on further publication. Kissinger, incredibly, dubbed Ellsberg “the most dangerous man in America” (the convenient title of a 2010 Oscar-nominated biopic that has been given new relevance, and more widespread screenings, by the WikiLeaks affair).

The pretext, of course, was national security—that continued exposure of details from a study officially classified “top secret” would do irreparable harm to the United States and its forces in Southeast Asia. Never mind that the Times had locked up an elite group of reporters and editors in a hotel suite for months to review the documents and compare what was already on the public record, in order to determine what was notable and worthy of public attention without putting the country or its troops at risk. In the context of an increasingly bitter atmosphere between Nixon and his critics—Vice President Spiro Agnew was routinely drawing cheers at the time with his attacks on the “nattering nabobs of negativism,” and reporters were being hauled before grand juries and told to reveal their sources about the Black Panther Party and other controversial topics or risk imprisonment—there were political points to be scored by pursuing the newspapers.

The pursuit was intense and, with the benefit of hindsight, sometimes absurd. During one closed hearing in US District Court in Washington, when the late Judge Gerhard Gesell was to determine what in the Papers might be dangerous if revealed, representatives of Nixon’s Justice Department insisted that the courtroom doors be locked and brown paper taped over their small windows, lest the reporters lurking in the hallway be able to learn new secrets by looking in and reading lips. Appellate court deliberations went into the night, and presses were stopped awaiting the outcome.

For all its months in court, the government was never able to prove the slightest harm to national security as a result of the Pentagon Papers’ disclosure. On the contrary, it is clear that the publication of the Pentagon Papers was immensely valuable as a contribution to the public dialogue about the Vietnam War. It did not end the conflict overnight, as Ellsberg might have hoped, but it certainly made opposition to it more acceptable and understandable.

History, Off Limits

It would be encouraging to believe that the government has learned important lessons from the Pentagon Papers case and other, less celebrated ones since then. But in fact the problem of secrecy and the inappropriate classification of information valuable to the public has grown dramatically in recent decades.

Sanford J. Ungar , author of The Papers & The Papers: An Account of the Legal and Political Battle Over the Pentagon Papers, which won a George Polk Award in 1972, is president of Goucher College in Baltimore and a member of the US Public Interest Declassification Board.