License Class: Public Domain Licenses
Works in the public domain are free for anyone to use without permission from the author of the work.
Otherwise copyrightable works can enter the public domain in a number of ways under U.S. law. Works authored by the U.S. Government enter the public domain because the government is prohibited from holding a copyright for its authored work. (17 US.C. Sec. 105). Other works enter the public domain when the copyright terms expires, because of a failure to satisfy statutory formalities under the Act prior to 1978, or by the author voluntarily placing the work into the public domain. The official copyright website states that, "[a] work of authorship is in the public domain if . . . the holder of the copyright disclaimed copyright in the work." (http://www.copyright.gov/help/faq/faq-definitions.html., last visited Sept. 24, 2010). Some explicit expression of the author's intent is required to place a work in the public domain. (4-13 Nimmer Sec. 13.03 [F]).
Some lawyers have expressed concern that a public domain dedication is problematic because it might be revoked at any time and it provides no protection for the creator against any damages caused by a work. (See http://www.linuxjournal.com/article/6225, last visited Sept. 24, 2010).
More problematic is the issue of conflicting interpretations of public domain in other jurisdictions. For example, many Europeans jurisdictions recognize moral rights, which makes public domain dedications difficult.