Holding a copyright gives you exclusive rights to use the work. However, there is an exception.
The U.S. Copyright Office explains the doctrine of fair use allows limited access to your copyrighted material by others. It helps to encourage expression and creativity without allowing for the complete abuse of copyrights. Determining whether a situation falls under fair use is not simple, but there are four general factors a court will consider.
Use
How the other party uses your work is important under fair use. Generally, the person should not be using it for profit. Courts will usually be ok with private, non-commercial use or use in educational settings. At the same time, if the user transformed the work in some way, such as adding something new, then that also is often approved under fair use.
Nature
The basic nature of the original piece is a factor because the court will typically consider more creative works to have more protection against fair use. Technical materials or those based on factual information often have more free reign under the doctrine.
Amount
In most cases, someone cannot use your full work under fair use. Courts will usually prefer only light use of a portion of the complete work.
Effect
If the use of your work is causing you a financial loss or otherwise reducing the value of your material, then the court will generally not allow it under fair use.
The fair use doctrine is complex. Judged always look at the specific situation, and rarely will they go on a set formula or compare one situation to another when making a decision. This is a legal process that runs on a case-by-case basis. For this reason, it is hard to know what a court may rule as allowable under the doctrine.