Section 107 of the US Copyright Laws in Title 17 (p.19) outlines the Fair Use Guidelines, which help determine whether the use of a copyrighted material without the copyright holder's permission is permissible:
(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 The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all the above factors.
The Fair Use Checklist
The Fair Use Checklist from Columbia University is licensed by a Creative Commons Attribution License with attribution to the original creators of the checklist Kenneth D. Crews (formerly of Columbia University) and Dwayne K. Buttler (University of Louisville).