Everyone — including lawyers and judges — likes
simple legal rules. And the copyright act seems to provide one,
with its fair use provision listing four factors. So determining
fair use should be as simple as adding up the scores on these four
factors, right?
Wrong. Really, really wrong. Fair use requires complex and
nuanced judgments, not simplistic arithmetic. Any arithmetical
method for determining fair use will almost always be
erroneous.
First, there aren't just four factors. Section 107 of the
Copyright Act, on fair use, calls for weighing all considerations,
which "shall include" the four factors it expressly
lists. In various cases, courts have considered other factors
beyond the ones listed, including the public interest, customs and
traditions, and the defendant's good faith.
