Fair use explained: the four factors and what they actually decide

Fair use is the most misunderstood doctrine in copyright, and the misunderstanding has a specific shape. People treat it as a set of permissions: a word count you can stay under, a percentage that is safe, a magic effect produced by adding credit or changing the colors. None of that is how the statute works.

Fair use is a defense, decided case by case, on four factors that courts weigh together. It is not a permission slip you qualify for in advance. And its most important factor was materially narrowed by the Supreme Court in 2023, which means a great deal of the fair use guidance still circulating online describes the law as it stood before that decision.

What is fair use?

Fair use is a statutory defense permitting certain unlicensed uses of copyrighted material. It is codified at 17 U.S.C. section 107, which directs courts to consider four nonexclusive factors. No single factor is dispositive, and all four are weighed together in light of the purposes of copyright.

Two features of that definition do most of the work. First, it is a defense rather than a right, which means it operates after a use has been challenged rather than before. You do not obtain fair use; you assert it, and a court decides whether it applies. Second, the factors are nonexclusive, so a court may consider matters outside the four listed.

The practical consequence is that fair use questions rarely have clean answers before litigation. Anyone who tells you with certainty that a particular use is fair is predicting how a court would weigh four open-ended factors, which is a forecast rather than a fact.

What are the four factors?

Section 107 sets out four considerations: the purpose and character of the use, 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 the original.

The third factor is where the numerical myths come from. There is no safe percentage in the statute and none in the case law. A short excerpt can defeat fair use if it captures the most significant part of the work, and a substantial taking can survive if the purpose genuinely requires it.

How did the Warhol decision change the analysis?

In Andy Warhol Foundation for the Visual Arts, Inc. v. Goldsmith, 598 U.S. 508 (2023), the Supreme Court held that the first factor weighed against fair use where the original work and the secondary use shared substantially the same purpose and the secondary use was commercial.

The facts matter for understanding the scope. Lynn Goldsmith photographed Prince. Warhol created a series of silkscreen works based on that photograph. After Prince died, the Warhol Foundation licensed one of those works, "Orange Prince," to Condé Nast for a commemorative magazine. Goldsmith's photograph had itself been licensed to illustrate magazine articles about Prince. In a 7-2 opinion by Justice Sotomayor, the Court concluded that both images were used to depict Prince in magazine stories about Prince, that the purposes were substantially the same, and that the first factor therefore favored Goldsmith.

The decision is narrower than its reputation. The Court addressed only the first factor and only the specific licensing use at issue, not the Prince Series works generally. But it shifted the inquiry in a way that matters broadly. Before Warhol, the first factor had increasingly turned on whether a new work was transformative in the sense of conveying a different meaning or message, and a finding of transformativeness tended to carry the other factors along with it. After Warhol, the question is closer to whether the use serves a practically different purpose than the original, with aesthetic transformation carrying less weight on its own.

This is the source of the currency problem in fair use guidance. Material written between the 2021 decision in Google LLC v. Oracle America, Inc., 593 U.S. 1 (2021), which found Google's copying of Java API declarations to be fair use, and the 2023 Warhol decision reflects a broader transformative-use standard that no longer holds in the same form.

Does transformative still matter?

Yes, but it is measured differently. The Court did not discard transformativeness. It reoriented the inquiry from how different the new work looks or feels toward whether the use serves a genuinely different function than the original.

The lineage helps here. In Campbell v. Acuff-Rose Music, Inc., 510 U.S. 569 (1994), the Court addressed 2 Live Crew's parody of Roy Orbison's "Oh, Pretty Woman" and observed that the more transformative a new work, the less significant other factors like commercialism become. Warhol did not overrule that framing. It clarified that the transformation must be assessed against the purpose and character of the particular use rather than the artistic character of the resulting work.

One distinction the Warhol Court drew is worth carrying forward: whether the secondary use targets the original. A use that comments on, criticizes, or parodies the source has an inherent justification for copying it, because the point cannot be made without the source. A use that borrows the source simply because it is useful raw material lacks that justification and needs some other one.

What does fair use not cover?

Several widely believed protections have no basis in section 107. Attribution is not a factor. Noncommercial status is relevant to the first factor but not decisive. And there is no length, percentage, or word count in the statute at all.

The attribution point deserves emphasis because it is so commonly assumed. Crediting the source is good practice for other reasons and may bear on a court's overall impression, but it is not one of the four factors and it does not cure infringement. In the Warhol litigation, the photographer was credited in most of the magazine uses at issue and the first factor still weighed against fair use.

The commercial-use point is subtler. Section 107(1) expressly names commercial nature as part of the first factor, so it matters. But nonprofit and educational use is not automatically fair either, particularly where the use substitutes for a licensing market that the copyright owner would otherwise serve. The fourth factor reaches potential markets rather than actual sales alone.

How should you evaluate a proposed use?

Start with purpose, because that is where the analysis now concentrates. Ask what function the original serves and what function your use serves, and be honest about whether those functions overlap. If your use would slot into the same market position as the original, the first factor is working against you regardless of how much you altered the material.

Then examine the fourth factor, which courts often treat as closely connected to the first. Consider whether your use substitutes for the original and whether it displaces a licensing market. Copyright owners license their work for many purposes, and a use that undercuts an existing or reasonably developable licensing channel faces a difficult fourth factor.

Take only what the purpose requires. The third factor asks about the heart of the work as well as the quantity, so excerpting the single most recognizable passage is riskier than a longer excerpt of ordinary material.

Finally, treat licensing as the alternative rather than the fallback. Where a license is readily available at a reasonable cost, the fourth-factor argument against fair use gets stronger, and the practical case for simply obtaining permission gets stronger with it.

For where the line falls in practice, see fair use versus copyright infringement. If the question is who owns a work rather than whether it can be used, start with work made for hire and copyright assignment versus license. Fair use is also the usual basis for a counter-notice when material is pulled down, which the DMCA takedown notice guide covers, and it stops mattering entirely once a work's term has run, which how long copyright lasts explains.

The U.S. Copyright Office publishes a searchable index of fair use decisions at copyright.gov/fair-use, and the full text of the statute is available at 17 U.S.C. section 107.

This article explains general legal principles and is not legal advice. Fair use is decided case by case and outcomes vary with facts. Consult an attorney before relying on fair use for a significant use.