There is no one right answer as to what constitutes a "fair use" of a particular copyrighted work. The answer varies from situation to situation.
A good starting point is to ask yourself this question: Have I made a good faith effort to comply with the "fair use" clause (Section 107) of U.S. Copyright Law?
Good Faith: Honesty; a sincere intention to deal fairly with others. (The Free Dictionary)
This report summarizes research into the current application of fair use to meet the missions of U.S. academic and research libraries. Sixty-five librarians were asked about their employment of fair use in five key areas of practice: support for teaching and learning, support for scholarship, preservation, exhibition and public outreach, and serving disabled communities.
Interviewees reported a strong commitment to obeying copyright law; rarely concerned about their own liability, librarians primarily felt responsible for ensuring their institutions were in compliance with the law. Practice varied considerably, from a rigid permissions culture to ample employment of fair use.
"Four factors" are considered in all fair use evaluations. They are:
1. The purpose and character of the use, including whether such use is of commercial nature or is for nonprofit educational purposes
2. The nature of the work wherein creative or expressive copyrighted works are given greater protection than works of a factual nature
3. The amount and substantiality of the portion used in relation to the copyrighted work as a whole
4. The effect of the use upon the potential market for, or value of, the copyrighted work
These four factors are not meant to be exclusive and must be examined together.
The statute does not indicate how much weight is to be accorded each factor. Historically the courts have placed the most emphasis on "effect", while the "nature" of the copyrighted work is usually considered to be the least important factor.
Use The Columbia University Fair Use Checklist to make a factual analysis concerning the cumulative “weight” of the factors favoring or opposing fair use. The checklist also serves as tangible evidence that you acted in good faith to apply fair use to meet your educational objectives.