Effect
Rationale: Effect on the market is
perhaps even more complicated than the other three factors. Some
courts have called it the most important factor, although such rhetoric
is often difficult to validate. This factor fundamentally means that
if you make a use for which a purchase of an original theoretically should
have occurred, regardless of your personal willingness or ability to pay
for such purchase, then this factor may weigh against fair use. "Effect"
is closely linked to "purpose." If your purpose is research or scholarship,
market effect may be difficult to prove. If your purpose is commercial,
then effect is presumed. Occasional quotations or photocopies may
have no adverse market effects, but reproductions of software and videotapes
can make direct inroads on the potential markets for those works.
Copyright
& Fair Use