Placing documents into the public domain

Most rights can be voluntarily abandoned ("waived") by the owner of the rights. Legislators can go to extra effort to create rights that can't be abandoned, but usually they don't do this.

In particular, you can voluntarily abandon your United States copyrights:

It is well settled that rights gained under the Copyright Act may be abandoned. But abandonment of a right must be manifested by some overt act indicating an intention to abandon that right. See Hampton v. Paramount Pictures Corp., 279 F.2d 100, 104 (9th Cir. 1960).

Micro-Star v. Formgen Inc., 154 F.3d 1107 (9th Cir. 1998).

Note for people not familiar with legal citations: After a "District Court" makes its decision in a United States court case, the losing party can appeal to the "Circuit Court of Appeals" that supervises the district court. These "Circuit Courts of Appeals" are manned by about 200 of the nation's most experienced judges. Each appeal is heard by three of these appellate judges; for example, the "Micro-Star v. Formgen" appeal was heard by Alex Kozinski, David R. Thompson, and Stephen S. Trott. Judge Kozinski, with agreement from the other two judges, wrote the decision in the case (in 1998). My quote is from Judge Kozinski's decision.

Does the public domain exist in Europe too?

Yes. You can voluntarily abandon your European copyrights. You can't abandon certain reputation rights (such as the right to stop people from removing your name from your work), but you can abandon your copyrights.

How do I place my work into the public domain?

The normal way to abandon a copyright is to make a clear written dedication of the work to the public domain. For example:

Most documents have a conventional location for a copyright notice (e.g., the bottom of page 1 of a scientific paper). You can write "Public domain" in this location rather than "Copyright 2005," "Copyright 2006," etc. This, by itself, clearly satisfies the "overt act" test.
You can write a subsequent document saying "I hereby place my paper `On The Origin Of Species' into the public domain." This, by itself, clearly satisfies the "overt act" test.

How do courts resolve disputes over public-domain status?

The Ninth Circuit Model Civil Jury Instructions, 2007 edition, Section 17.19, states a model for the text that courts give to juries:

17.19 COPYRIGHT - AFFIRMATIVE DEFENSE - ABANDONMENT
The defendant contends that a copyright does not exist in the plaintiff's work because the plaintiff abandoned the copyright. The plaintiff cannot claim ownership of the copyright if it was abandoned. In order to show abandonment, the defendant has the burden of proving each of the following by a preponderance of the evidence:
1. the plaintiff intended to surrender [ownership] rights in the work; and
2. an act by the plaintiff evidencing that intent.
Mere inaction [, or publication without a copyright notice,] does not constitute abandonment of the copyright; however, [this may be a factor] [these may be factors] for you to consider in determining whether the plaintiff has abandoned the copyright.
If you find that the plaintiff has proved [his] [her] [its] claim[s] in accordance with Instruction[s] [insert cross reference to the pertinent instructions on the plaintiff's theory of infringement], your verdict should be for the plaintiff, unless you find that the defendant has proved each of the elements of this affirmative defense, in which event your verdict should be for the defendant.

See also Section 20.19 in the 2001 edition.

Isn't it impossible to place work into the public domain?

Lawrence Rosen is a lawyer who makes money helping people create, and comply with, complicated copying conditions. In an essay titled "Why the public domain isn't a license," Rosen claims that a clear written dedication of a copyrighted work to the public domain doesn't actually abandon copyright. In particular, Rosen claims that "Intellectual property enters the public domain only when it grows old" and that "There is no mechanism in the law by which an owner of software can simply elect to place it in the public domain."

If you see a Ninth Circuit panel writing "It is well settled that rights gained under the Copyright Act may be abandoned," and then a lawyer making the opposite claim, you probably expect the lawyer to explain the contradiction. Rosen doesn't do this. In fact, he doesn't seem to be aware that he's contradicting anybody, let alone three federal judges and the Ninth Circuit Model Civil Jury Instructions.

Let's look at the details of Rosen's argument:

Rosen claims an analogy between littering and abandoning a copyright: "Just as there is nothing in the law that permits a person to dump personal property in the public highway, there is nothing that permits the dumping of intellectual property into the public domain."
In fact, there are laws against littering, and those laws put considerable limits on the ways in which you can abandon your real property. There are no laws against abandoning a copyright.
Rosen claims that placement into the public domain is a "gift" that "cannot be enforced" (under "basic contract law") and that can be "retract[ed] at any time." He says that this is "scant security for someone intending to make long-term use of a piece of software."
Rosen doesn't seem to understand the differences between waivers, gifts, and contracts. It's true that a gratuitous promise, a contract without "consideration," generally can't be enforced: someone who makes a promise, without being promised anything in return, can retract the promise. But this has no relevance to a gift that has been given; a donor cannot demand that his gift be returned. It also has no relevance to a right that has been waived.
Rosen claims that public-domain software can't be distributed "as is," without warranty. Rosen also observes, correctly, that public-domain software allows recipients to "make secret changes to the donated software and re-release the changed version to the world for a fee under a proprietary license."
This part of Rosen's essay follows his general "Public domain is evil!" theme but obviously doesn't support his "Public domain is nonexistent!" claim.

If these are the best arguments that Rosen can come up with, I'm not surprised to see judges saying that they're "settled" on the opposite position.