Movies based on novels, paintings based on photographs, even poems that consist entirely of direct transcriptions of newspaper editions: there are many examples of artistic endeavors that could be considered derivative works. Classifying them as such could open them up for arguments concerning copyright infringement. California tech companies should also be aware that many of these rules may also apply to software projects.
One could argue that there are always influences at play, even when someone creates an original work. Influence is, therefore, not the issue when it comes to establishing a piece's derivative nature. To be subject to copyright infringement laws, a piece would usually have to be completely dependent on its predecessor.
A work's derivative nature does not invalidate it legally or artistically. It would, however, usually require acknowledgment of and tribute to the creating authority.
While there are usually costs associated with obtaining permission to use protected material, there are also risks associated with not doing so. As explained by the U.S. Copyright Office, intellectual property found to derive from a copyright-protected source could lose part of its own copyright protections in some cases.
Another risk involves infringement claims. Those who create derivative works without the original author's or copyright holder's permission could leave themselves open to a lawsuit. However, claimants might find it difficult to prove infringement in some cases. For example, Rolling Stone's report on the contentious, high-profile infringement case involving Led Zeppelin illustrates the obstacles many of these cases could face.
The trial discussed in Rolling Stone resulted in a jury decision favoring the defense. It is a demonstration of the fact that similar works are not necessarily derivative, and that claimants should make an effort to organize and present their cases carefully.