Fair use is written into United States copyright law, which lists four factors for courts to consider when making fair use decisions: the new user's purpose, the nature of the original work being used, the amount of the original work being used, and the effect of the use on the market for the work being used. One way to synthesize these four factors is to ask two questions:
- Are you planning on using the work in a different way, or for a different purpose, than the original creator? In copyright terms, is your use transformative?
- Are you using an amount of that work that is appropriate to your new purpose?
If you are unsure, seek legal counsel.
