One of the most common misconceptions about fair use is that it's always authorized for academic and teaching purposes. "Fair use" does not give you carte blanche for instructional uses, and it is not a conversational term. Fair use is a statutory exemption that is essential to academic use through application of the fair use doctrine, but commercial uses also can be fair, and academic ones can be not fair.
The Fair Use Doctrine Section 107 of the Copyright Law allows you to apply the statutory exemption, for each use when you are engaging in a copyright holder's exclusive rights. It affords you the legal opportunity to determine if you can use a copyrighted work without permission, under certain circumstances, if specific criteria are met, and when the exemption's analysis is applied for each incidence of your use.
Can you apply the statutory exemption for fair use? Use it if you are:
The Fair Use Four Factor Test is the standard for determining fair use. All four factors must be applied to each use and all factors must be weighed, or balanced, for a final judgment of fair. Copyright is balance, seeking a reasonable use for the person who does not have exclusive rights to use the copyrighted work, and protecting the copyright holder's interest and contributions, and incentive for future works. Applying the fair use test provides the balance between creators and users.
There are four factors that must be considered and balanced. One factor is applicable to you and what you are doing with the copyrighted work, and the other three are applicable to the copyrighted work:
An easy to use, online test is available at the University of Texas Copyright Crash Course. The test uses conversational language and a columnar format for applying the four factor fair use test. It provides a good visual for determining whether or not your use is on the correct side of the test for fair use, or in the middle where a re-evaluation and modification of your use might tip the balance in favor of fair use.
Fair Use is not a right...it is a defense to an infringement claim. Apply the four factor test if the work is protected and you feel your use of the copyrighted work might fall under the fair use doctrine, and always document your determination. Fair Use is a balance...affording the copyright holder certain rights while also encouraging others to use the work to build new knowledge. Each time fair use is applied, it strengthens the climate that affords the balance of the copyright holder's exclusive rights and others' use to promote the progress of knowledge.