The Fair Use Doctrine is probably the most important exemption to copyright protections for educational settings, allowing many uses of copyrighted works for the purposes of teaching and research. However, not all use is fair use, simply because it occurs in an academic setting.
The four factors to be considered in determining whether or not a particular use is fair:
The distinction between fair use and infringement may be unclear and not easily defined. There is no specific number of words, lines, or notes that may safely be taken without permission. Acknowledging the source of the copyrighted material does not substitute for obtaining permission.
The safest course is always to get permission from the copyright owner before using copyrighted material. The Copyright Office cannot give this permission.
When it is impracticable to obtain permission, use of copyrighted material should be avoided unless the doctrine of fair use would clearly apply to the situation.
- From the web site of the U.S. Copyright Office
The Association of Research Libraries publishes the Code of Best Practices in Fair Use for Academic and Research Libraries. The document was developed in partnership with the Center for Social Media and the Washington College of Law at American University.