Gibson Guitar Corp. (Gibson) (plaintiff) had been producing musical instruments, including guitars, for over 100 years. Paul Reed Smith Guitars, LP (PRS) (defendant) began producing custom guitars in the mid-1970s. Gibson first produced its well-known Les Paul guitar in 1952. Gibson submitted a drawing to the United States Patent and Trademark Office (PTO) and applied to register its solid-body, single-cutaway Les Paul guitars in 1987. The registration was approved in 1990. In 2000, PRS began manufacturing guitars in the same style as Gibson’s Les Paul guitars, with slight differences in proportions and size. Gibson sent PRS a cease and desist letter and then sued for an injunction. Gibson admitted that there was no evidence that consumers actually confused the products. Instead, the court found that there would likely be some initial confusion prior to the consumer’s purchase of PRS’s guitar as to its source because Gibson’s Les Paul, particularly its shape, was so famous. Therefore, the district court granted Gibson an injunction against PRS. PRS appealed this decision.