Fair Use

In 1841, the Supreme Court heard the case of Folsom v. Marsh. Justice Story, in his decision, wrote that a derivative work may not be infringing if it is a "justifiable use of the original materials." This was the beginning of the doctrine of fair use which would come to serve as an important "gray zone" between copyrighted works and their use.

In 1970, this right was codified. Section 107 of the Copyright Act allows for the use of copyrighted material without consent for purposes of, among others, scholarship, criticism or reporting. However, the exemption is hardly well-defined. Congress provided four factors to consider in deciding whether or not a use is fair:

1. the purpose and character of the use, including whether such us is of commercial nature or is for nonprofit educational purposes;
2. the nature of the copyrighted work;
3. 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.
   

Fair use is what allows book reviewers to quote a novel or news programs to use other stations materials. It is essential to the global conversation on every topic: from politics to literature.

However, as mentioned above, fair use is not a clear-cut right. Often, a rights holder can scare an unknowing fair user with a cease and desist letter (see examples here).

Fair Use Resources:

Stanford University has an extensive resource guide for fair use.

The Copyright Office has a short page on fair use.

The Fair Use Network is an organization commit

American University (with the help of many others) wrote the Documentary Filmmakers' Statement of Best Practices in Fair Use which gives information which is relevant to more than just movie makers.