Recently, the have been a number of court cases where the plaintiff sought to narrow or restrict the public domain. In one of the most direct attacks, CBS sued a YouTube user who posted certain episodes of the Andy Griffith show which were individually in the public domain by claiming that these episodes were derivative works from other episodes which remained under copyright. There have also been lawsuits centering on the character of Sherlock Holmes and certain materials made relating to the Wizard of Oz. In looking at the news of these lawsuits and evaluating them, it is helpful to know precisely what the public domain is, why it is important, and how it has evolved over time.
What is the public domain?
The public domain consists of works which are not covered by copyright or other intellectual property restrictions. These are works which anyone may use as they choose, such as by republishing them, performing, or creating a new work based on the public domain work.
Intellectual works may become part of the public domain in a number of ways. Many seminal works, such as the plays of William Shakespeare, were created before copyright came into existence and have always been in the public domain. Some works, such as creations of the U.S. Federal Government, may not be covered by copyright and are in the public domain. Other works that were covered by copyright entered the public domain
when their copyrights expired, such as the “The Scream” by Edvard Munch.
Until relatively recently, bringing a work under the protection of copyright required that certain formalities be observed. Most creators did not bother to have their works registered and protected by copyright.
There are also certain things which may not be covered by copyright and are thus in the public domain. Copyright provides protection for the specific expression in question, and does not cover ideas, scènes à faire, or commonly used tropes. It also does not cover facts. All of these things, which may be embodied in a particular work, become part of the public domain as soon as they made public.
What is the importance of the public domain?
As someone who writes academically, writes software, and dabbles in creative writing, I rather like the concept of authors creating their works ex nihilo. But that concept does not fit my own experiences. My code uses libraries provided by others and techniques taught to me by other programmers. My academic work is explicitly based on the work that comes before it and filled with citations. My attempts at creative work often show subtle signs of being inspired by other works I have been exposed to. Most, if not all, creative work draws inspiration if not full elements from the work of previous generations. The public domain provides much of the fodder which makes this creativity using elements provided by others legal. In fact, Jessica Litman, a prominent copyright scholar has said “the public domain is the law’s primary safeguard of the raw material that makes authorship possible.” Many new works are based on public domain works. Disney in particular is well known for creating adaptations of works that are in the public domain.
How was the public domain created?
In one sense, the public domain has existed for as long as humans have created. However, the concept of the public domain as a distinct thing only arose when there were government granted monopolies on intellectual property to contrast it with. Although there were earlier precursors, the first modern patent law was the Statute of Monopolies and the first modern copyright law was the Statute of Anne. Early copyright laws tended to provide protection for quite a short time by modern standards, and the work would join the public domain when the protection expired.
How has the public domain changed over time?
Perhaps the most significant recent development is that, because of copyright extensions, the public domain in the United States has grown very little. The most recent extension, passed in 1998 in the Sonny Bono Copyright Term Extension Act, extended the copyright term by 20 years. It has been argued that a major motivation behind passing that law was to prevent some of the earliest movies containing Mickey Mouse from entering the public domain.
The constitutionality of that extension was challenged by Eric Eldred and a team of lawyers which included Lawrence Lessig and Geoff Stewart, but it was upheld in Eldred v. Ashcroft. Because of the Sonny Bono Copyright Term Extension Act, no published works will enter the public domain through expiration of copyright until 2019. It is quite possible that certain copyright holders will seek, and may even get, another copyright extension prior to 2019.
 The public domain comes up in reference to any and all forms of intellectual property. However, it tends to be most controversial, and arguably most significant, in context of copyright. This post thus focuses primarily on copyright matters.
 “The Scream” was completed in 1893, and since it was published before 1923 it is in the Public Domain in the United States. See Copyright Term and the Public Domain in the United States, Cornell (2016) available at http://copyright.cornell.edu/resources/publicdomain.cfm; see also WIPO, The Arts and Copyright, 41 (2007) (using The Scream as an example of a public domain work that is frequently used by other creators). Although Edvard Munch died in 1944, his works have not entirely entered the public domain in the United States based on that due to copyright extensions. Duke Law, Public Domain Day: January 1, 2015 – For Other Eyes Only, Center for the Study of the Public Domain (January 1, 2015).
 Lawrence Lessig, Remix 262-263 (2008)
 See Capcom Co. v. MKR Group, Inc., 2008 U.S. Dist. LEXIS 83836, at *19-20 (N.D. Cal. Oct. 10, 2008) (Discussing elements which must be “filtered out” when examining substantial similarity in the context of the Dead Rising video game and Dawn of the Dead movie.)
 “Scènes à faire” translates as scenes which must be done.
 See generally Backer v. Selden, 101 U.S. 99 (1879) (finding that the idea of a proposed bookkeeping system could not be protected by copyright.)
 James Boyle, The Public Domain: Enclosing the Commons of the Mind 207 – 209 (2008).
 Jessica Litman, The Public Domain, 39 Emory L. J. 965, 980 (1990); see also Stowe v. Thomas, 23 F. Cas. 201 (C.C.E.D. Pa. 1853) (finding that aspects of the Uncle Tom’s Cabin which were not protected by the copyright law then in effect could be used by others.)
 Jessica Litman, The Public Domain, 39 Emory L. J. 965, 966-967 (1990). See also Jack Anderson, Critic’s Notebook: Dance and the Influence of others, N.Y. Times, Apr. 9, 1989.
 Jessica Litman, The Public Domain, 39 Emory L. J. 965, 966-967 (1990); Jay Worthinton, Righting Copyright: An Interview with Lawrence Lessig, Cabinet (2002) (“Creativity builds upon the public domain”).
 The Statute of Anne authorized a copyright term of 14 years, with a possible renewal for one additional term. Statute, 1710, 8 Ann., c. 19; see also H. Tomas Gomez-Arostegui, The Untold Story of the First Copyright Suit under the Statue of Anne in 1710, 25 Berkley Tech. L. J. 1247, 1248 (2010). The first U.S. federal copyright statute also granted a term of 14 years that could be renewed once. Jessica Litman, The Public Domain, 39 Emory L. J. 965, 978 (1990).
 What Could Have Entered the Public Domain on January 1, 2017?, Center for the Study of the Public Domain, last accessed Feb 03, 2017.
 Lawrence Lessig, Free Culture 134 (2004).
 Timothy B. Lee, 15 Years ago, Congress kept Mickey Mouse out of the public domain. Will they do it again?, The Washington Post (October 25, 2013).
 Lawrence Lessig, Remix 228-248 (2008).