“Fair use” is the single most important limitation on copyright in the United States on which writers are likely to rely. Several other countries have fair use rules of their own, or related-but-different “fair dealing” rules, but keep in mind that how fair use works in practice is likely to vary from place to place.
Writers can make fair use of a copyrighted work without getting permission from the rightsholder or paying for a license. But fair use is always case-specific, meaning there are no hard or universal rules setting out what it does or does not allow. Instead, fair use requires careful, individualized, consideration and balancing of four factors:
- The purpose and character of the use.
- The nature of the copyrighted work.
- The amount and substantiality of the portion used in relation to the copyrighted work as a whole.
- The effect of the use upon the potential market for or value of the copyrighted work.
In the event of a legal dispute, fair use determinations are ultimately made by courts. Over time, these court decisions have provided more guidance as to what is or is not fair use — consulting these decisions, or a lawyer familiar with them, can provide significantly more clarity as to whether a given use would be considered fair.
Lear more here on what you should know when relying on fair use.