A FURTHER EXPLANATION OF "FAIR USE"
from Lesley Ellen Harris, author of Canadian Copyright Law, 3rd ed. (McGraw-Hill Ryerson)
In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include -
(1) the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit 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.
The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all the above factors.
Fair use is not defined but is left open for a court to decide whether a particular use might be subject to this defence on a case-by-case basis, taking into account certain factors as enumerated in the provision. This intended flexibility is the cause of much confusion and its interpretation of much debate. It is clearly the intention of the U.S. Congress to leave fair use open to interpretation and new technology based upon a court's consideration of any particular case before it.
In determining whether any one situation of copying is fair use, a court must consider all the above four criteria.
However, the Copyright Act does not further define these factors, which are intentionally vague, and it does not provide guidance as to the weight to be given to any one factor or whether the factors must be equally weighed in a Court's determination.