Only expression of idea copyright-protected, not idea itself

Baker v. Selden, 101 U.S. 99, was a leading Supreme Court of the United States (US) copyright case cited to explain the idea-expression dichotomy.

In Baker vs. Selden , the US Supreme Court held that only the expression of an idea is protected by copyright, not the idea itself. In that case, the plaintiff held the copyright of a book which expounded on a new accounting system he had developed. The publication illustrated blank forms of ledgers utilized in such a system. The defendant reproduced forms similar to those illustrated in the plaintiff’s copyrighted book.

The following is the analysis of the US Supreme Court:"There is no doubt that a work on the subject of book-keeping, though only explanatory of well known systems, may be the subject of a copyright; but, then, it is claimed only as a book. But there is a clear distinction between the books, as such, and the art, which it is, intended to illustrate. The mere statement of the proposition is so evident that it requires hardly any argument to support it. The same distinction may be predicated of every other art as well as that of bookkeeping. A treatise on the composition and use of medicines, be they old or new; on the construction and use of ploughs or watches or churns; or on the mixture and application of colors for painting or dyeing; or on the mode of drawing lines to produce the effect of perspective, would be the subject of copyright; but no one would contend that the copyright of the treatise would give the exclusive right to the art or manufacture described therein. The copyright of the book, if not pirated from other works, would be valid without regard to the novelty or want of novelty of its subject matter. The novelty of the art or thing described or explained has nothing to do with the validity of the copyright. To give to the author of the book an exclusive property in the art described therein, when no examination of its novelty has ever been officially made, would be a surprise and a fraud upon the public. That is the province of letters patent, not of copyright. The claim to an invention of discovery of an art or manufacture must be subjected to the examination of the Patent Office before an exclusive right therein can be obtained; and a patent from the government can only secure it.

"The difference between the two things, letters patent and copyright, may be illustrated by reference to the subjects just enumerated. Take the case of medicines. Certain mixtures are found to be of great value in the healing art. If the discoverer writes and publishes a book on the subject (as regular physicians generally do), he gains no exclusive right to the manufacture and sale of the medicine; he gives that to the public. If he desires to acquire such exclusive right, he must obtain a patent for the mixture as a new art, manufacture or composition of matter. He may copyright his book, if he pleases; but that only secures to him the exclusive right of printing and publishing his book. So of all other inventions or discoveries.

"The copyright of a book on perspective, no matter how many drawings and illustrations it may contain, gives no exclusive right to the modes of drawing described, though they may never have been known or used before. By publishing the book without getting a patent for the art, the latter is given to the public.

"Now, whilst no one has a right to print or publish his book, or any material part thereof, as a book intended to convey instruction in the art, any person may practice and use the art itself which he has described and illustrated therein. The use of the art is a totally different thing from a publication of the book explaining it. The copyright of a book on bookkeeping cannot secure the exclusive right to make, sell and use account books prepared upon the plan set forth in such book. Whether the art might or might not have been patented, is a question, which is not before us. It was not patented, and is open and free to the use of the public. And, of course, in using the art, the ruled lines and headings of accounts must necessarily be used as incident to it.

"The plausibility of the claim put forward by the complainant in this case arises from a confusion of ideas produced by the peculiar nature of the art described in the books, which have been made the subject of copyright. In describing the art, the illustrations and diagrams employed happened to correspond more closely than usual with the actual work performed by the operator who uses the art. The description of the art in a book, though entitled to the benefit of copyright, lays no foundation for an exclusive claim to the art itself. The object of the one is explanation; the object of the other is use. The former may be secured by copyright. The latter can only be secured, if it can be secured at all, by letters patent."