A largely US defense to copyright and trademark infringement codified in §107 of the US Copyright Act. Fair use finds its origins in free speech rights and allows the limited use of copyrighted materials or a trademark for purposes of comment, satire and parody (typically of the work itself.) It is a difficult defense to assert, and can be undermined (though not necessarily fatally) if the purpose of the use is for profit rather than comment, academic discussion, teaching or humor or if the ‘taking’ is substantial or total (i.e., the whole work rather than small parts is used) and how “transformative” the new work is; however, members of the public often perceive the scope of the defense as much more extensive than it actually is – or argue for it in situations where it simply cannot apply. The burden of proving a fair use defence is on the infringer, and the defence necessarily amounts to an implicit admission of taking the copyrighted work (i.e., lose and you may have effectively admitted infringement.)
A number of legal systems have no clear recognition of the concept of fair use, e.g., Germany, France, the Netherlands, Spain, Sweden, and Switzerland, and in those countries where it exists, the scope of the defense is highly variable. See also, Fair Dealing, Incidental Copying.