The effect of the use upon the potential market for or value of the copyrighted work.
In Napster’s case, their platform allowed for “repeated and exploitative” copying, which met the meaning of the first factor, even though no sales were taking place. In addition, songs were found to be “close to the core” of the types of creative works intended to be protected by copyright, and entire songs were downloaded, setting the second and third factors against Napster. Finally, the effect of the downloads was found to harm possible album sales, which was the final nail in the coffin of Napster’s argument in favor of a fair use defense