The "fair use" defense to copyright infringement is one of the most amorphous legal doctrines.  Originating in the U.S. courts, and adopted by only a few other countries, it allows "fair" use of copyrighted works without authorization from the owner. The fair use doctrine furthers the constitutional purpose of promoting "the progress of science and useful arts," and has been characterized as fundamental to defending freedom of expression under the First Amendment.  But how much and what use is "fair" versus what use will end up being declared copyright infringement often feels like guess work, especially because courts have arrived at different conclusions when faced with the same or very similar fact patterns. This causes some artists, authors and other creators to refrain from borrowing material from an already existing work, which arguably unduly hinders creativity. Recent case law in this area, including from the U.S. Supreme Court, has done little to bring clarity to this already murky area, but some general principles still hold true, which we discuss here.

The test for fair use is a multi-factor test in which all the statutory factors are balanced against each other. Section 107 of the Copyright Act enumerates some types of uses in which fair use is likely to be found such as criticism, comment, news reporting, teaching, scholarship or research. However, this list is not exhaustive and the need to balance all statutory factors means that other purposes have also been found fair in case law.