Derivative Works: When Can You Legally Build on Someone Else’s Copyrighted Work?

Creative works rarely exist in complete isolation. Authors build on stories they have read, filmmakers adapt novels, musicians rearrange compositions, and artists reinterpret earlier works. Copyright law recognizes these creative relationships, but it also places limits on how one person may use another person's protected expression.

A derivative work generally involves creating something new from an existing copyrighted work. The legal issue is whether the creator has the right to make that adaptation.

What Makes a Work “Derivative”?

A derivative work takes protected material from an earlier work and changes, adapts, or recasts it into another form.

Common examples include:

• Turning a novel into a screenplay;

• Translating a book into another language;

• Creating a stage production from a copyrighted story;

• Reworking a copyrighted musical composition;

• Creating a sequel that uses protected characters and story elements; or

• Making an adaptation of an existing fictional work.

Not every new work that is inspired by an earlier work is legally derivative. Copyright protects particular forms of expression, not every underlying idea or concept.

That distinction can be decisive.

When an Adaptation Is Authorized

The simplest situation is one in which the copyright owner has given permission.

Copyright owners can license others to create adaptations. The permission can be broad or narrowly defined. For example, an agreement might allow someone to create a motion picture based on a novel but say nothing about television, merchandise, or other uses.

The terms of the agreement therefore matter. A person should not assume that permission to use a work for one purpose automatically includes permission to adapt it for another.

Public-Domain Material

A copyrighted work does not remain protected forever. When copyright protection expires, the underlying work generally enters the public domain.

That can provide considerable creative freedom. A writer may create a new story based on a public-domain novel without asking the original author for permission because the copyright in that underlying work has expired.

There is an important catch: the public-domain status of one work does not necessarily extend to later versions of it.

Suppose an old novel is in the public domain, but a modern movie based on that novel is still protected by copyright. A filmmaker may be free to draw from the old novel while remaining prohibited from copying original material added by the modern movie.

Knowing exactly what source material is being used is therefore essential.

Fair Use Can Permit Some Unauthorized Uses

U.S. copyright law also recognizes fair use. In appropriate circumstances, a person may use copyrighted material without obtaining permission.

Fair use is particularly important where the new work serves purposes such as criticism, commentary, news reporting, teaching, scholarship, or parody. But the doctrine is broader than a simple list of permitted categories, and no particular type of project automatically qualifies.

Courts evaluate the circumstances of the particular use. Among other considerations, they examine the purpose of the new work, the characteristics of the original work, the amount used, and the consequences for markets for the original.

A commercial project is not automatically excluded from fair use, just as a noncommercial project is not automatically protected.

Changing the Original Work Does Not Automatically Make It Legal

One of the most persistent misconceptions about derivative works is that changing enough details makes copying lawful.

It does not work that way.

Adding new material, changing a character's name, moving a story to another location, or rewriting portions of a work does not necessarily eliminate copyright concerns if protected expression from the original remains substantially present.

Likewise, there is no magic percentage—such as changing 10%, 25%, or 50%—that automatically makes an adaptation permissible.

Copyright analysis focuses on the substance of what was taken and how it was used, not simply on how many words, scenes, characters, or details were changed.

Inspiration Versus Copying

Copyright law leaves room for creators to be influenced by existing works.

An author can take inspiration from the premise of another story while creating different characters, dialogue, scenes, and expressive details. The same basic concept can sometimes support many independently created works.

For example, the idea of a detective solving a crime is available to everyone. A particular author's distinctive detective, dialogue, sequence of events, and detailed fictional world may not be.

The challenge is determining where inspiration ends and appropriation of protected expression begins.

Open Licenses Can Provide Permission

Some copyright owners deliberately give the public permission to use their works under specified conditions.

Creative Commons licenses are one familiar example. Depending on the particular license, an author may permit adaptations while imposing requirements concerning attribution, commercial use, or licensing of the resulting work.

The important point is to read the actual license. "Free to use" is not necessarily the same thing as "free to use for any purpose."

The Practical Question

Before adapting someone else's work, a creator should ask:

What am I actually taking?
Is it an idea, historical fact, or general concept—or protected creative expression?

Is the source still copyrighted?
If not, the public-domain status may eliminate the need for permission.

Do I have a license?
If so, what does the license actually authorize?

Could an exception apply?
Fair use and other limitations may permit certain uses without authorization.

What is the commercial and legal risk?
A project intended for publication, distribution, licensing, or commercial exploitation deserves particular attention before significant resources are invested.

Bottom Line

Creating something new from an existing copyrighted work is not automatically unlawful. But neither does adding new material automatically make the resulting work permissible.

The legality of a derivative work depends on the source material, the rights involved, the nature and extent of the use, any permission that has been granted, and whether a statutory limitation such as fair use applies.

For creators, the safest approach is to identify the protected material before beginning the adaptation and determine what legal right supports the intended use. When substantial commercial interests are involved, a copyright attorney can evaluate the particular project before it is released to the public.

This article is for general informational purposes and does not constitute legal advice. Copyright law is fact-specific, and the outcome of any particular situation may depend on the applicable law and circumstances.