Answer: Copyright law seeks to promote the production and distribution of creative works by conferring property rights on authors. The principle of fair use serves to mediate between these property rights and the constitutional rights of public access and free speech embodied in the First Amendment. Fair use serves an important social function by allowing for the use of parts of creative works for the sake of criticism, commentary, and reporting.

To decide whether a use is "fair use" or not, courts consider:

1. the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit education 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.[17 U.S.C. 107(1-4)]

The principles of fair use are invoked when the transaction costs associated with gaining authorization from copyright owners to make use of works is too burdensome in reasonable circumstances. Fair use also permits the reproduction of art and information for the private, noncommercial sharing of those works. Fair use allows for market competitors to use copyrighted works in ways that allow them to extract the public domain aspects of those works in order to develop innovative products.