Navigating Copyright Law and Fair Use for Photographers
Techdirt. Stories filed under "fair use" 2013-04-03
Summary:
"An important thing to remember is that the loss of a licensing fee that the copyright owner would have charged the unauthorized user who is claiming fair use does not count. Otherwise, the fourth factor would have to be found in favor of the copyright owner in every case.
Remember, there are no absolute rules regarding fair use. When in doubt (which is just about every situation involving fair use), talk to a competent copyright lawyer."