The concept of “fair use” applies to US legal systems, and similar systems of “fair dealing” exist in the United Kingdom and other Commonwealth nations. Fair use refers to the users’ right to use, in the following ways, works that are protected under intellectual property: to report a news story, to make a parody, to make a copy for educational purposes, to quote in academic works, and to critique works. However, these uses alone do not determine whether or not an expression falls under the doctrine of fair use. Four factors, often considered in relation to one another, complicate fair use in US legal proceedings (the purpose of the use, the nature of the copyrighted work, the amount and significance of the part used in relation to the copyrighted work, and the effect that such use may have on the market or value of the copyrighted work). In practice, fair use is quite ambiguous, because relatively little US case law exists in relation to fair use claims. To avoid costly legal proceedings, many people opt not to push fair use, and choose instead to pay licensing fees in advance, including these as part of production costs. However, choosing this option closes down the creative possibilities that exist under the doctrine of fair use.