Fair use is a legal doctrine that promotes freedom of expression by permitting the unlicensed use of copyright-protected works in certain circumstances.
Section 107 of the Copyright Act calls for consideration of the following four factors in evaluating a question of fair use:
(1) Purpose and character of the use,
including whether the use is of a commercial nature or is for nonprofit educational purposes;
(2) Nature of the copyrighted work;
(3) Amount and substantiality of the portion used in relation to the copyrighted work as a whole;
(4) Effect of the use upon the potential market for or value of the copyrighted work.
In addition to the above, other factors may also be considered by a court in weighing a fair use question, depending upon the circumstances. Courts evaluate fair use claims on a case-by-case basis, and the outcome of any given case depends on a fact-specific inquiry. This means that there is no formula to ensure that a predetermined percentage or amount of a work—or specific number of words, lines, pages, copies—may be used without permission (US Copyright Office).
The Fair Use Index, created by the US Copyright Office, is an online database that tracks and summarizes major fair use judicial decisions. Each judicial decision includes a brief summary of the facts, the relevant question(s) presented, and the court's determination as to whether the contested use was fair.
Innovation Partnership services is happy to answer any questions you may have about copyright, fair use, and how it relates to commercialization.
The UO Copyright Clearance Center, part of Printing and Mailing services, can assist in reviewing materials you'd like to reproduce and help you decide if it is indeed Fair Use or if permissions are needed.
The College Art Association provides an excellent document on Frequently Asked Questions (FAQs) on Fair Use with detailed answers.