As an author or an artist, you may encounter problems if you incorporate all or part of someone else's creation in your work, known as derivative work claims.
Many artists thrive on using material from popular culture to create art with a message. From distorting Barbie's appearance in order to counter the idea that white, blond, and thin are female ideals, to reworking the classic Gone With the Wind from the perspective of a slave and half-sister of Scarlet O'Hara, these artists recognize that our culture benefits from a rich public domain. One commentator said it best: "Cultural works and inventions don't spring from an utter vacuum. They are the product of other people's ideas and works. Practically every melodic theme in music comes from older works, for example."
In order to preserve the incentive for artists and authors to produce works, American copyright law grants creators a limited monopoly right to create works based on or derived from the original creation (derivative works). The law strikes an uneasy balance between an author's or artist's right to profit from their works and other artists' and authors' right to build upon previous works to make new works.
For example, the trial court halted the publication of the novel The Wind Done Gone because it used elements and characters from Gone With the Wind. But the appellate court let the novel be published, holding that the use of those characters and elements was protected under the law. In other cases, artists have produced paintings or photographs and another artist sells copies of the images pasted to floor tiles or tee-shirts. Whether the first artist has a viable copyright violation cause of action against the second artist for violating her right to produce derivative works turns on whether the second artist's appropriation of the first artist's material constitutes fair use
What's a "derivative work"?
Congress revised the federal copyright statute in 1976 to provide copyright owners with statutory protection for derivative works. A derivative work can take the form of "any . . . work [that] may be recast, transformed, or adapted. A work consisting of editorial revisions, annotations, elaborations, or other modifications which, as a whole, represents an original work of authorship, is a 'derivative work.'" 17 U.S.C. 107 (1-4)
Also, your work may be using an element from another work that is not copyrightable, like a story line or a stock character.
If you received a cease and desist letter claiming your art is an unauthorized derivative work, this information should help you understand the law to which the letter refers. Unfortunately, even the law does not always draw an obvious line between works that are derivative and works that are not.