Doctrine of Fair Use

The legal doctrine of Fair Use grew out of common law concerns for protection of author’s works while promoting freedom of expression through permission of certain unlicensed uses of copyright-protected works.. The legal framework identifies criticism, comment, news reporting, teaching, scholarship, and research as examples of situations in which quoting an author’s work qualifies as Fair Use. The legal concept of Fair Use was codified into US law in the Copyright Act of 1976. 

Examples of Fair Use include purpose and character of the use (such as  education or criticism), the nature of the copyrighted work (fictional works borrowing from a copyrighted source are less likely to support a fair use claim), quantity of the use of copyrighted material, and whether the use of the copyrighted work damages the marketability of the quoted work. Other factors may be considered in a fair use challenge. Each court evaluates the merits of a copyright infringement challenge on a  case-by-case basis.