Can my work be copyrighted if it is based on a public domain work?

A work based on a public domain work can be copyrighted, provided that your own work (which is called a “derivative work”) passes the so-called “threshold of originality”. That means that your (new) work should be characterized by creativity and originality, that are the imprint of your authorship. Then this new work will deserve copyright protection.

Think in layers. The lower layer is the work in the public domain. Think of any public domain work or character you may use for your derivative work. Now you add an additional layer that originates from your creativity (plot, script, other characters, situations, locations, etc.). This layer has to be creative, otherwise it will not be protected by copyright. If creative, then this new layer is protected by copyright. Anyone can use the public domain layer without the need to ask permission by the right holder (that’s the concept of public domain) however no one can use your layer, the one you created.

The same structure applies even if your derivative work is based on a previous work that is still protected. The lower layer is the original author’s layer, then you add on top an additional layer of yours. In this case, not being there any public domain situation to help, whoever wants to use your work shall ask permission to both you (the top layer) and the original author (the lower layer). If you want to use your work (the top layer) by yourself, you shall anyway ask the original author’s permission (the lower layer).

This is why a work based on an original work that is in the public domain can be anyway protected by copyright.


United States

In United States copyright law, the principle of requiring originality for copyright protection was invoked in the 1991 ruling of the United States Supreme Court in Feist Publications v. Rural Telephone Service. The court opinion stated that copyright protection could only be granted to "works of authorship" that possess "at least some minimal degree of creativity". As such, mere labor ("sweat of the brow") is not sufficient to establish a copyright claim. For example, the expression of some obvious methods of compilation and computation, such as the Yellow Pages or blank forms, cannot receive a copyright (demonstrated in the Court of Appels case Morrissey v. Procter & Gamble done in June 28, 1967), but sufficiently original elements within the work itself can still be eligible for protection. 

It is an old “chestnut” in the law that phone books cannot be copyrighted — they are just lists of data including plain names and numbers.