Sometimes it is OK to copy some portion of a copyrighted work. That “sometimes” is called “fair use” and acts as a defense to a claim of copyright infringement.
While the copyright statute sets out four factors for a court to consider in determining whether the use of a copyrighted work is a fair use, there is no bright-line test. This is what courts call a “mixed question of law and fact” which means that it all depends on the particular circumstances of each case. To blur the line even more, the four factors are non-exclusive meaning that a court is free to consider anything else that might be relevant as well.
The four non-exclusive fair use factors are set out in the Copyright Act at 17 U.S.C. ยง 107:
All of these factors are to be weighed together when evaluating fair use.
The first factor relates to how the alleged infringer is using the work. Under this factor, noncommercial, nonprofit, educational, parody, commentary and criticism activities all weigh in favor of fair use. Alternatively, using the infringing work to make money or as part of a business would weigh against finding fair use.
The second factor considers the nature of the copyrighted work. Under this factor, copying primarily informational works rather than primarily creative works weighs in favor of fair use. Alternatively, copying fiction, visual arts, or music would weigh against a finding of fair use.
The third factor considers the amount of the worked copied. Under this factor, copying a small amount of the work, rather than the entire work weighs in favor of fair use. Alternatively, copying the whole work would weigh against a finding of fair use.
The fourth factor considers the effect the alleged infringement has on the potential market for the work. Under this factor, if the alleged infringement in no way act as a replacement for the original work, this factor will weigh in favor of fair use. Alternatively, if after viewing the infringing work, a consumer is less likely to want or need to view the original, this factor would weigh against a finding of fair use.
In summary, whether a use a is a fair use all depends on the facts and circumstances surrounding the alleged infringement. As is typical in the law, “it depends.” If you think you are using too much of a work, you probably are. Often the best course of action is to ask permission or seek out guidelines from the copyright owner.