Idea–expression distinction

The idea–expression distinction or idea–expression dichotomy is a legal doctrine in the United States that limits the scope of copyright protection by differentiating an idea from the expression or manifestation of that idea.

Unlike patents, which may confer proprietary rights in relation to general ideas and concepts per se when construed as methods, copyrights cannot confer such rights. An adventure novel provides an illustration of the concept. Copyright may subsist in the work as a whole, in the particular story or characters involved, or in any artwork contained in the book, but generally not in the idea or genre of the story. Copyright, therefore, may not subsist in the idea of a man venturing out on a quest, but may subsist in a particular story that follows that pattern. Similarly, if the methods or processes described in a work are patentable, they may be the subject of various patent claims, which may or may not be broad enough to cover other methods or processes based on the same idea. Arthur C. Clarke, for example, sufficiently described the concept of a communications satellite (a geostationary satellite used as a telecommunications relay) in a 1945 paper that was not considered patentable in 1954 when it was developed at Bell Labs.