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.
Many Germans incorrectly believe that copyrights cannot be abandoned. The actual situation in German law is that "Nutzungsrechte" (literally "usage rights") include the rights of copying, modification, distribution, etc.; these rights can be waived, as in other countries. "Urheberrechte" (literally "originator rights") include reputation rights and generally cannot be waived, but this protection against fraud, libel, etc. has nothing to do with whether something is in the public domain. Beware that many sources (including Google Translate) mistranslate "Urheberrecht" as "copyright"; this contributes to the common confusion among Germans on this topic.
17.19 COPYRIGHT - AFFIRMATIVE DEFENSE - ABANDONMENTSee also Section 20.19 in the 2001 edition.
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.
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:
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 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.
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.
2012.09.22 update: In a public message this year, Rosen admitted that "at least in the Ninth Circuit, a person can indeed abandon his copyrights (counter to what I wrote in my article)". He didn't give any further analysis of his errors, and he didn't state any reason to think that this (quite elementary) legal issue would be decided differently by any other courts. He did finally withdraw his recommendation against "public domain" dedications:
I admit that I have argued for years against the "public domain" as an open source license, but in retrospect, considering the minimal risk to developers and users relying on such software and the evident popularity of that "license", I changed my mind.