Although the shorter the excerpt the better, even the use of an entire work may be appropriate if it is necessary to your teaching needs and is not reasonably available for purchase. Commercial uses tend to have more impact on the market, and nonprofit educational uses have less impact on the market. Given the unique situation of classroom settings, Congress has limited the financial liability that educators might face, assuming that educators make reasonable and good faith efforts at abiding by fair use guidelines. Challenges to the fair use of copyrighted material for educational uses almost never become matters for court decisions. It is also noteworthy that university indemnification policies often protect individual faculty from personal litigation by means of reimbursing faculty for damage awards and attorney's fees.
Good faith increases the likelihood that activities are in fact fair use.
Good faith reduces the risks of liability in the event of infringement. However, faculty who knowingly violate established policy may not be able to claim good faith and thus may not fall under indemnification policies. One should presume that all Web pages, e-mail messages, and newsgroup messages are copyrighted unless clearly stated otherwise. Copyright holders thus retain all rights to copy, distribute, display, perform, and create derivative works from their internet creations. Although we should presume that the material in web pages is copyrighted, the page owner does not have the right demand that others are prohibited from linking to his page.