Unclear US Rules
The rules on declaring a work public domain before the copyright expires under united-states law are less then clear. In a sense, there are no such rules. There is no provision in 17 USC, the current US copyright law, for doing so by any means. The US copyright office will record declarations that a work has been donated to the public domain, but they express no opinion on the legal validity of such declarations. My understanding is that courts have been inconsistent on this issue, and some courts have held that such declarations have no legal effect at all.
However, if a notice that the document is in the public domain was placed with the permission of the copyright holder, a court would probably find that estoppel or perhaps, the "unclean hands" doctrine prevented the holder from collecting damages in a suit for infringement. Even if the notice was not authorized, a reuser would probably count as an "innocent infringer".
Still it might be wise to verify the intent of any such notice, and that it is actually authorized by the copyright holder. All of this is true regardless of any involvement of the US Federal Government.
Sources
Justia's page on "Works in the Public Domain" says:
A copyright owner can choose to surrender their rights in a certain work. This means that the work is released into the public domain so that anyone can use it. The owner must make an express and unambiguous statement of their intent. You should not assume that a work has been dedicated to the public domain unless it is very clear. Sometimes this occurs through a Creative Commons CC0 license, but this is not the only method.
But it cites no law or authority for this statement. Nolo's page on "How Can I Use Copyright-Free Works (in the Public Domain)?" takes a similar view, saying:
Millions of works have been dedicated to the public domain. This means the author or other copyright owner chooses to give up all rights in the work forever. This is often done online using a Creative Commons CC0 license.
However, using a CC0 license is not required. A copyright owner's use of any words unequivocally dedicating a work to the public domain can suffice, for example, words such as "this work is dedicated to the public domain and may be reproduced without authorization.”
Unless there is express authorization placing the work in the public domain, do not assume that the work is free to use.
Again, no law or caselaw supporting these statements is cited.
Even assuming that the position taken by Justia and Nolo is legally correct, one must be careful. Only an action by the copyright holder or at the holder's express direction would suffice to put a work in the public domain. If an agent, authorized to publish a work on a web site, attaches a "public domain" notice without the holder's direction, perhaps through misunderstanding, such a notice would not place the work in the public domain.
The Authors' Alliance page on "Paths to the Public Domain" says:
In theory, a copyright owner can voluntarily abandon her copyright prior to the expiration of the work’s copyright term by engaging in an overt act reflecting the intent to relinquish her rights. Abandoned works then become part of the public domain, free from copyright and available for anyone to use.
Creative Commons offers a “No Rights Reserved” tool for copyright owners who wish to waive copyright interests in their works and thereby place them as completely as possible in the public domain. And recently, satirist Tom Lehrer added a statement to his website granting permission to the public to download and reuse his lyrics, noting that they “should be treated as though they were in the public domain.” That said, a scholarly article by Dave Fagundes and Aaron Perzanowski criticizes the current state of the law surrounding copyright abandonment. The authors assert that the lack of a clear, reliable way to abandon copyright frustrates authors who wish to abandon their copyrights, and the practical effectiveness of abandonment is undermined by the lack of a broadly accessible record of abandoned works.
On another page from the Author's Alliance there is a summary of the article by Fagundes and Perzanowski, which reads:
In a new article, Abandoning Copyright, Dave Fagundes, Professor of Law at the University of Houston, and Aaron Perzanowski, Professor of Law at Case Western Reserve University, review the doctrine of copyright abandonment and suggest reforms to facilitate copyright abandonment and promote a richer public domain.
Copyright abandonment refers to the voluntary and permanent relinquishment of an owner’s rights in a copyrighted work prior to the expiration of the work’s copyright term. In general, an author abandons her copyright by forming an intent to relinquish her rights and engaging in an overt act reflecting that intent. Abandoned works become part of the public domain, free from copyright and available for anyone to use. Fagundes and Perzanowski propose that copyright law should facilitate the legal and administrative process of abandonment, suggesting that doing so would realign copyright law with the constitutional intent of incentivizing creation to enrich the public.
The authors acknowledge that abandoning copyrights prevents an author from extracting the economic value of a work that is derived from exploiting exclusive rights. In addition, an author who abandons copyright also gives up the ability to prevent uses to which they would object. However, the public welfare is greatly benefited as the work becomes freely available for anyone to access and use. As such, abandonment can encourage new creative production by making more “raw material” available for other creators to use in their own works, whether it be original creation or derivative works (the authors point to examples of multiple movie adaptations based on literary works in the public domain, such as Alice in Wonderland, Peter Pan, The Jungle Book, Sherlock Holmes, King Arthur, and Robin Hood).
Fagundes and Perzanowski criticize the current state of the law surrounding copyright abandonment: The lack of a clear, reliable way to abandon copyright frustrates authors who wish to abandon their copyrights, and the practical effectiveness of abandonment is undermined by the lack of a broadly accessible record of abandoned works. The Copyright Act of 1976 contains no explicit provision on how an author may opt out of copyright law’s grant of economic rights. They also highlight that although the U.S. Copyright Office records notices of abandonment, it does not indicate whether such recordation is legally effective in actually abandoning the copyrights. Finally, they point out that the doctrine of abandonment is ill-defined and courts are inconsistent in their rulings, often mixing abandonment with other doctrines such as forfeiture or waiver. They ultimately conclude that these shortcomings might discourage authors who would otherwise be inclined to abandon their works because the practice appears inaccessible.
The abstract of the article published by Case Western Reserve Law School, and starting on page 487 of the journal reads:
For nearly two hundred years, U.S. copyright law has assumed that owners may voluntarily abandon their rights in a work. But scholars have largely ignored copyright abandonment, and the case law is fragmented and inconsistent. As a result, abandonment remains poorly theorized, owners can avail themselves of no reliable mechanism to abandon their works, and the practice remains rare. This Article seeks to bring copyright abandonment out of the shadows, showing that it is a doctrine rich in conceptual, normative, and practical significance. Unlike abandonment of real and chattel property, which imposes significant public costs in exchange for discrete private benefits, copyright abandonment is potentially costly for rights holders but broadly beneficial for society. Nonetheless, rights holders — ranging from lauded filmmakers and photographers to leading museums and everyday creators — make the counterintuitive choice to abandon valuable works. This Article analyzes two previously untapped resources to better understand copyright abandonment. First, we survey four decades U.S. Copyright Office records, demonstrating both the motivations for abandonment and the infrequency of the practice. Second, we examine every state and federal copyright abandonment case, a corpus of nearly 300 decisions. By distilling this body of law, this Article distinguishes abandonment from a set of related doctrines and reveals the major fault lines in judicial application of the abandonment standard. Finally, we highlight the potential of abandonment to further copyright’s constitutional aims by suggesting a series of reforms designed to better align copyright holder incentives with the public good.
Starting On Page 535 of Abandoning copyright, the authors say:
Of the remaining 162 decisions that squarely address
abandonment, only seventeen found that the works in question had,
in fact, been abandoned. ...
Our examination of these decisions suggests that, not unlike their
chattel property counterparts, the copyright abandonment cases
reveal considerable confusion, uncertainty, and inconsistency. First,
courts have failed to reliably distinguish between abandonment
and a number of related, but conceptually and practically distinct
doctrines. In part, this confusion reflects the extent to which abandonment
was doctrinally intertwined with the formalities that
prevailed in copyright law prior to the 1976 Act. Since then, courts
have delineated some of these doctrines more clearly. ,,, Second, aside from the bare recitation of the common law
test for abandonment, a fully realized and consistently applied
doctrine has yet to take shape. Given the paucity of cases in which
abandonment defenses prevail, it remains difficult to predict with
much confidence which acts courts will deem sufficient evidence of
the subjective intent to abandon. ...
... courts frequently refer to “abandonment” when cases actually
present a question of forfeiture.301 At other times, courts blur the
line between abandonment and a number of related, but distinct
doctrines including acquiescence, waiver, estoppel, and implied
license. ...
... Public domain status is best understood as the
legal consequence of both abandonment and forfeiture. While the
term “dedication” implies some degree of intent, courts often refer
to forfeiture as a public domain dedication.3 In any case, dedication
is not a distinct doctrine with its own legal standard. Notably,
copyrights in certain foreign works that were in the public domain
were restored by the Uruguay Rounds Agreement Act in 1996 if
they were forfeited, but not if they were abandoned. ...
Estoppel and acquiescence compound the problem. As the
Supreme Court recently clarified, estoppel applies “when a copyright
owner engages in intentionally misleading representations
concerning his abstention from suit, and the alleged infringer
detrimentally relies on the copyright owner's deception.”317 Acquiescence
is best understood as a type of estoppel. It turns on express or
implied assurances made by the copyright holder to the defendant
that it will not assert its copyright.318 This focus on reliance
distinguishes estoppel and acquiescence from abandonment. Like
waiver, even if estoppel or acquiescence can be established, the
copyright holder retains ownership and the ability to enforce its
copyright against the rest of the world. ...
... Bates v. Keirsey (No. D041368, 2004 WL 2850153 (Cal. Ct. App. Dec. 13, 2004).) presents an easy case of abandonment.332 The
authors and copyright holders of the book Please Understand Me
wanted to import copies from Hong Kong.333 In order to avoid the
manufacturing clause, Bates and Keirsey signed a document
entitled “Abandonment of Copyright” that read, in part, “We hereby abandon our copyright to the book titled Please Understand Me.”
The court was convinced that the “evidence unequivocally established” that Bates engaged in an overt act demonstrating his intent to abandon.
...
Melchizedek v. Holt (792 F. Supp. 2d 1042, 1045 (D. Ariz. 2011).) concerned the copyright in a meditation video. In an open letter, the creator of the video explained that he “let the
video go out to the world unrestrained. No control on the copyrighted
material. No money coming back to me from the videos.”350
He went on to explain that he “never cared about the copyrights
[and] wanted the information to go out to the world.” Later, he
told workshop attendees that he “do[es]n't care about copyrights or
any of that stuff, that doesn't matter.” Nonetheless, the court
found the evidence insufficient to establish abandonment.