The "Oath of a Freeman" was a loyalty oath drawn up in the early 17th century, to be taken by freemen of the Plymouth Colony, in the Commonwealth of Massachusetts; a freeman was any established member of a colony who was not under legal restraint. The Oath was a vow to defend the Commonwealth, and not to conspire to overthrow the government. It was first written in 1631, and revised in 1634. Original copies survive only in a handwritten copy from 1634 and in a later printed version from 1647. Stephen Daye made a broadside printing of the document in 1639, but it is now lost.
A supposed copy of Daye's printing surfaced in 1985 and was touted as the oldest surviving print in the United States, but it was revealed to be the work of prominent forger Mark Hofmann.
Hofmann's "Oath" was the last of his forgeries, and was created as a final, desperate attempt to recover from financial hardship. Hofmann produced two copies of the Oath, which were bid upon by the Library of Congress and the American Antiquarian Society for over $1.5 million; authentication of the prints was underway when Hofmann began planting bombs in Salt Lake City to stall for time in another one of his schemes. The bombs killed two people and injured Hofmann himself, and police uncovered evidence of his forgeries during the ensuing investigation. The affair was the subject of the City Confidential episode "Faith and Foul Play in Salt Lake City", Forensic Files episode "Postal Mortem", as well as the Canadian series Masterminds, in an episode called "The Anthon Forgeries".
The "Oath of a Freeman" is also the subject of a work of contemporary literary fiction by J. F. Newman, titled The Freeman's Oath.