What statutory factors decide whether use of a copyrighted work is fair use?
Section 107 makes fair use of a copyrighted work not an infringement, and lists four factors a court weighs: purpose and character of the use, nature of the work, amount used, and market effect.
The answer
Fair use is not infringement
17 U.S.C. § 107 provides that the fair use of a copyrighted work, including for purposes such as criticism, comment, news reporting, teaching, scholarship, or research, is not an infringement of copyright. The section then lists the factors a court must consider.
The four factors
The statute directs courts to weigh the purpose and character of the use, including whether it is commercial; the nature of the copyrighted work; the amount and substantiality of the portion used; and the effect of the use on the potential market for or value of the work.
The judged input
What the AI drafted
Submitted to the judgeThis is an excerpt from a draft copyright infringement advisory memo — the kind of work product a lawyer generates with a legal-AI drafting tool, then has to stand behind. Kingsfield does not write it; it rules on the citations the model put in it. This draft cites two authorities; one of them is wrong.
The judge ruled on every citation as the draft used it — it accepted 17 U.S.C. § 107 and rejected 17 U.S.C. § 106. Here is why.
The verdict
How Kingsfield ruled
Ruled 2026-06-23Each citation in the draft above was submitted to the Kingsfield judge and ruled against the primary-law corpus — Accept, Reject, or Inconclusive, per citation. These are live verdicts, not editorial. Each card shows the claim the draft made and the verbatim authority the verdict was rendered against.
The draft claimed: The fair use of a copyrighted work is not an infringement, and in determining fair use a court considers the purpose and character of the use, the nature of the work, the amount and substantiality of the portion used, and the effect of the use upon the potential market for the work.
“§ 107 Notwithstanding the provisions of sections 106 and 106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not…”
Cite found; proposition supported by the cited text.
The draft claimed: Section 106 sets out the fair use defense and the four factors a court weighs in deciding whether an otherwise infringing use is excused as fair use.
Cite found, but the cited text does not support the claim. 17 U.S.C. 106 grants the copyright owner the exclusive rights (reproduction, derivative works, distribution, public performance and display); the fair use defense and its four factors are at 17 U.S.C. 107. Regenerate with the correct authority.
Run your own work through the judge
Kingsfield rules on every citation, quote, and proposition your AI produces, against the primary law we cover. Accept, Reject, or Inconclusive, per citation, with a signed Audit Capsule.
Connect the Judge See the architectureThis page is legal information, not legal advice, and does not create an attorney-client relationship. The draft shown is an illustration of a typical AI answer; verdicts reflect the cited authority in the Kingsfield corpus as of the ruling date shown above.