Unlike the other limitations discussed so far, the Fair Use Doctrine does not offer “bright-line” rules. Fair use is outlined in §107 of the Act, and confers on courts the ability to decide when some action should constitute infringement and when not: “Notwithstanding the provisions of sections 106 and 106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include—

(1) the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes; (2) the nature of the copyrighted work; (3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and (4) the effect of the use upon the potential market for or value of the copyrighted work. The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all of the above factors.”

The U.S. differs from most other countries by providing a fair use doctrine, rather than simply specifying specific allowable actions. In the U.S., fair use finds its origin in Folsom v. Marsh (9 F. Cas. 342 (C.C.D. Mass. 1841)), drawing on the British doctrine of “fair abridgement”, where Justice Story argued that centrally important to consideration are: “the nature and objects of the selections made, the quantity and value of the materials used, and the degree in which the use may prejudice the sale, or diminish the profits, or supersede the objects, of the original work.” Because fair use is judged on a case-by-case basis, determining whether or not a use is “fair” can be exceedingly difficult.

One normative theory for fair use is that certain otherwise- infringing uses advance the development of a common culture (educational, critical, reporting uses). Harper & Row, Publishers, Inc. v. Nation Enterprises 471 U.S. 539 (1985) The Four Factors: o Purpose & Character of the Use o Nature of the Copyrighted Work o Amount & Substantiality of Portion Used o Effect on the Market

Campbell v. Acuff-Rose Music, Inc. 510 U.S. 569 (1994) The Four Factors: o Purpose & Character of the Use o Nature of the Copyrighted Work o Amount & Substantiality of Portion Used o Effect on the Market

Bill Graham Archives v. Dorling Kindersley Ltd. 448 F.3d 605 (2d Cir. 2006) The Four Factors: o Purpose & Character of the Use o Nature of the Copyrighted Work o Amount & Substantiality of Portion Used o Effect on the Market

As a practical matter, achieving interoperability between computer programs often requires copying protected elements of copyrighted programs in order to figure out how to make a new program compatible with an existing one. The resulting program may or may not supplant a copyrighted work. Sega Enterprises Ltd. v. Accolade, Inc. 977 F.2d 1510 (9 th Cir. 1992) The Four Factors: o Purpose & Character of the Use o Nature of the Copyrighted Work o Amount & Substantiality of Portion Used o Effect on the Market

Perfect 10, Inc. v. Amazon, Inc. 508 F.3d 1146 (9 th Cir. 2007) The Four Factors: o Purpose & Character of the Use o Nature of the Copyrighted Work o Amount & Substantiality of Portion Used o Effect on the Market Sony Corporation of America v. Universal City Studios, Inc. 464 U.S. 417 (1984)

The “market failure” theory is that a use is presumptively “fair” if it overcomes some market flaw that otherwise prevents consensual exchange of intellectual goods—such as goods being prohibitively expensive for use but where such use is of high value for society with little economic harm. A&M Records, Inc. v. Napster, Inc. 239 F.3d 1004 (9 th Cir. 2001) The Four Factors: o Purpose & Character of the Use o Nature of the Copyrighted Work o Amount & Substantiality of Portion Used o Effect on the Market