regard as fair use under the circumstances: "quotation of excerpts in a
review or criticism for purposes of illustration or comment; quotation
of short passages in a scholarly or technical work, for illustration or
clarification of the author's observations; use in a parody of some of
the content of the work parodied; summary of an address or article, with
brief quotations, in a news report; reproduction by a library of a
portion of a work to replace part of a damaged copy; reproduction by a
teacher or student of a small part of a work to illustrate a lesson;
reproduction of a work in legislative or judicial proceedings or
reports; incidental and fortuitous reproduction, in a newsreel or
broadcast, of a work located in the scene of an event being reported."

Although the courts have considered and ruled upon the fair use doctrine
over and over again, no real definition of the concept has ever emerged.
Indeed, since the doctrine is an equitable rule of reason, no generally
applicable definition is possible, and each case raising the question
must be decided on its own facts. On the other hand, the courts have
evolved a set of criteria which, though in no case definitive or
determinative, provide some gauge for balancing the equities. These
criteria have been stated in various ways, but essentially they can all
be reduced to the four standards which have been adopted in section 107:
"(1) the purpose and character of the use, including whether such use is
of a commercial nature or is for non-profit 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."

These criteria are relevant in determining whether the basic doctrine of
fair use, as stated in the first sentence of section 107, applies in a