The Pentagon Papers, officially titled United States–Vietnam Relations, 1945–1967: A Study Prepared by the Department of Defense, were a top-secret United States Department of Defense history of the United States' political-military involvement in Vietnam from 1945 to 1967. Commissioned by United States Secretary of Defense Robert S. McNamara in 1967, the study was completed in 1968. The papers were first brought to the attention of the public on the front page of the New York Times in 1971.
The study was classified as top secret and was not intended for publication. Contributor Daniel Ellsberg, however, turned over most of the Pentagon Papers to New York Times reporter Neil Sheehan, with Ellsberg's friend Anthony Russo assisting in their copying. The Times began publishing excerpts in a series of articles on June 13, 1971. Street protests, political controversy and lawsuits followed.
To ensure the possibility of public debate about the content of the papers, on June 29, US 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.
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" He added that he leaked the papers to end what he perceived to be "a wrongful war".