The Pentagon Papers true title is United States–Vietnam Relations, 1945–1967: A Study Prepared by the Department of Defense, a 47-volume, 7,000-page, top-secret Department of Defense history of the United States' politico-military involvement in the war in Vietnam, from 1945 to 1967.
U.S. Secretary of Defense Robert S. McNamara commissioned the study in 1967, and appointed Leslie Gelb (Pentagon international security affairs policy planning-arms control director) as study supervisor. Gelb hired 36 military officers, civilian policy experts, and historians to write the study's monographs. The Pentagon Papers included 4,000 pages of actual documents from the 1945–67 period.
Daniel Ellsberg gave most of the Pentagon Papers to New York Times reporter Neil Sheehan, with Ellsberg's friend Anthony Russo assisting in their copying. The NYT began publishing excerpts as an article-series on June 13, 1971. Political controversy and lawsuits followed; on June 29, U.S. Senator Mike Gravel (then Democrat, Alaska) entered 4,100 pages of the Papers to the record of his Subcommittee on Public Buildings and Grounds. These portions of the Papers were subsequently published by Beacon Press, the publishing arm of the Unitarian Universalist Association of Congregations.
The importance of recording the Papers to the Congressional Record was that, Article I, Section 6 of the United States Constitution provides that "for any Speech or Debate in either House, [a Senator or Representative] shall not be questioned in any other Place", thus the Senator could not be prosecuted for anything said on the Senate floor, and, by extension, for anything entered to the Congressional Record, allowing the Papers to be publicly read without threat of a treason trial and conviction.
Later, Ellsberg said the documents "demonstrated unconstitutional behavior by a succession of presidents, the violation of their oath and the violation of the oath of every one of their subordinates", and that he had leaked the papers in the hopes of getting the nation out of "a wrongful war."
The Pentagon Papers revealed many things, among them, that the US deliberately expanded its war with airstrikes against Laos, coastal raids of North Vietnam, and U.S. Marine Corps attacks — before President Lyndon B. Johnson informed the American public, though promising to not expand the war. The revelations widened the credibility gap between the U.S. government and the American people, hurting the Nixon administration's war effort.
Anthony Lewis comments in the law course taught by James Goodale (ex-NYT-house-counsel), Old Media, New Media, that the NYT was legally advised to not publish. Goodale counselled otherwise: the press had a First Amendment right to publish information significant to the people's understanding of their government's policy. Yet, President Richard Nixon argued that Ellsberg and Russo were guilty of felony treason (per the Espionage Act of 1917), because they had no authority to publish classified documents.
A credibility gap of which the NYT wrote was that a consensus to bomb North Vietnam had developed in the Johnson administration on September 7, 1964, before the U.S. presidential elections, however, per the Papers, none of the consensus actions recommended on September 7 involved bombing North Vietnam. On June 14 1971, the NYT said the Johnson administration began last plans for the bombing in November.
Another controversy was that President Johnson sent combat troops to Vietnam by July 17, 1965, after pretending to consult his advisors on July 21–July 27, per the cable stating that
The New York Times' publication of the Pentagon Papers article-series angered President Nixon; he told National Security Advisor Henry Kissinger: people have gotta be put to the torch for this sort of thing ... and let's get the son-of-a-bitch in jail. After failing to persuade the NYT to voluntarily cease publication, U.S. Attorney General John N. Mitchell and President Nixon obtained a federal court injunction forcing the NYT to cease publication. The newspaper appealed the injunction, and the case quickly rose through the U.S. legal system to the Supreme Court.
On June 18, 1971, the Washington Post began publishing its own series of articles based upon the Pentagon Papers; Ellsberg gave portions to editor Ben Bagdikian. That day, Assistant U.S. Attorney General William Rehnquist asked the Washington Post to cease publication; they refused; Rehnquist sought an injunction; the U.S. district court refused him; the Government appealed the refusal.
On June 26, the Supreme Court agreed to hear both cases, consolidating to the 'New York Times Co. v. United States' (403 US 713). On June 30, 1971, the U.S. Supreme Court decided, 6–3, that the injunctions were unconstitutional prior restraint and that the Government failed to meet the heavy burden of proof required for prior restraint injunction. The nine justices wrote nine opinions disagreeing on significant, substantive matters; while generally a victory for First Amendment free speech absolutists, others felt it a mild legal victory of little protection for publishers against national security claims to prior restraint of publishing.
Thomas Tedford and Dale Herbeck summary of the editorial and publishing reaction of the time: