Is there another branch of the merger doctrine in the United States?

There is another branch of the merger doctrine which has prevailed in the United States and which it is necessary to consider. It would appear to have originated with the decision in Baker v. Selden (1879), 101 U.S. 99, a case referred to in several "commonwealth" decisions,[16] but without reliance on the full scope of the decision given therein. Baker v. Selden dealt with copyright claimed in a book which described a new system of accounting and particularly accounting forms (consisting of certain ruled lines and headings) contained in the book. The court found that the defendant's use of the book and development of his own forms did not breach the plaintiff's copyright — i.e., there was no substantial copying. But the court went further and drew a distinction between works of science or instruction and other types of works. It held that where a useful art could only be employed by using the forms or diagrams by which it was explained there would be no copyright in such forms and diagrams.[17]