Fair Use vs Copyright Infringement: Where Exactly Is the Line?

A YouTuber named Cass made a 12-minute video reviewing a film. She used about 90 seconds of clips from the film, mostly to illustrate points she was making about the cinematography. The studio’s automated system flagged her video for copyright infringement. She countered with a fair use claim. The system rejected the counter. She appealed. Eventually a human reviewed it and the claim was released.

Was that fair use? Almost certainly yes. Did the system know that on first pass? No. This is the actual reality of fair use in 2026: a legitimate defense that platforms enforce inconsistently because the test was designed for humans applying judgment, not algorithms making fast decisions.

Here’s how fair use actually works, when it applies, and where the bright lines are.

What fair use is, and what it isn’t

Fair use is a doctrine in US copyright law (codified at Section 107 of the Copyright Act) that lets you use copyrighted material without permission in certain circumstances. It’s an affirmative defense, which means it doesn’t make your use legal in advance. It gives you grounds to defend the use if you’re sued.

That distinction matters more than most people realize. A copyright holder can still send a takedown notice or file a lawsuit even when your use is clearly fair. You then have to demonstrate the fairness in response. The cost of that defense, even when you win, can be substantial.

Outside the US, the equivalent concept is “fair dealing” and it’s almost always narrower. UK fair dealing covers specific enumerated purposes (research, criticism, news reporting, parody) and doesn’t have the flexible four-factor analysis US fair use does. EU member states each have their own list of permitted exceptions. Canada and Australia have fair dealing systems closer to the UK model but with their own twists.

For the rest of this article, “fair use” refers to US doctrine. The basic intuitions apply elsewhere but the specific test does not.

The four-factor test

Section 107 lists four factors a court is supposed to consider when deciding whether a use is fair. They’re not a mechanical checklist. They’re considerations to be weighed together, with no factor automatically dispositive.

Factor 1: Purpose and character of the use

Is the use commercial or non-commercial? Is it transformative (adding new meaning, expression, or purpose) or merely substitutive (replacing the need to buy the original)?

This factor leans toward fair use when the use is:

• Non-commercial (educational, personal, scholarly)
• Transformative (parody, commentary, criticism, news reporting)
• For a fundamentally different purpose than the original

It leans against fair use when the use is:

• Commercial
• Substitutive (you’re using the work for the same purpose as the original)
• A copy or near-copy of the original without significant transformation

The transformative use concept has been the most important development in fair use over the past 30 years. A use that recontextualizes the original work, comments on it, parodies it, or repurposes it for a fundamentally different aim is much more likely to be fair, even when commercial.

The Supreme Court’s 2023 decision in Andy Warhol Foundation v. Goldsmith complicated this somewhat. Warhol’s silkscreens of a Lynn Goldsmith photo of Prince, the court held, were not transformative enough to be fair use in the specific commercial licensing context at issue. The decision narrowed the transformative use defense without eliminating it.

Factor 2: Nature of the copyrighted work

This factor asks what kind of work was used. Some types of work are closer to the “core” of copyright protection and get stronger protection. Some are more on the periphery.

This factor tends to lean toward fair use when:

• The original is factual or informational (lower creative content)
• The original has been published (vs unpublished)

It tends to lean against fair use when:

• The original is highly creative (fiction, art, music)
• The original is unpublished (the author hasn’t had a chance to publish on their own terms)

In practice, factor 2 has been the least influential of the four factors. Most fair use decisions turn on factors 1, 3, and 4.

Factor 3: Amount and substantiality of the portion used

How much of the original did you use? Was it a small portion or the entire work? And was the portion you used the “heart” of the work, the most important part?

This factor leans toward fair use when:

• You used a small portion
• The portion you used wasn’t the work’s most significant element

It leans against fair use when:

• You used the entire work
• You used the most distinctive or important portion (even if quantitatively small)

The “heart of the work” idea matters. Using a 30-second clip from a 2-hour film can still weigh against fair use if those 30 seconds are the climactic scene. Using 200 words from a 100,000-word novel could weigh against fair use if those 200 words are the most quoted passage. Quantitative analysis alone isn’t enough.

Factor 4: Effect on the market for the original

Does your use substitute for the original in the market? Does it diminish sales of the original or licenses for the original? Does it create a derivative market that the original author would normally control?

This is the factor courts tend to weigh most heavily. It leans toward fair use when:

• Your use doesn’t substitute for buying the original
• Your use doesn’t diminish licensing revenue the original author would normally collect

It leans against fair use when:

• Your use causes readers/viewers to skip buying the original
• Your use occupies a market the original author would normally license to

A book review that quotes 500 words to discuss a novel doesn’t substitute for buying the novel. It might actually drive sales. Fair use favored.

A pirate website that hosts the full text of the novel obviously substitutes for buying the novel. Fair use heavily against.

Cases that won

Some uses have been clearly held to be fair use. These are the precedents you can rely on.

Parody. A parody of a copyrighted work, even a commercial one, is typically fair use. 2 Live Crew’s parody of Roy Orbison’s “Oh, Pretty Woman” was held fair use in Campbell v. Acuff-Rose Music (1994). The Supreme Court emphasized that parody by definition needs to use elements of the original to make its point.

News reporting. Quoting and excerpting copyrighted material in news coverage is generally fair use, especially when the news value couldn’t be served without the quotation.

Criticism and commentary. A film review using clips from the film. A book review quoting passages. A music critic discussing specific lines from a song. All generally fair use when the use serves the critical purpose.

Search engines and indexing. Google’s reproduction of book pages in Google Books was held fair use in Authors Guild v. Google (2015) because the index served a transformative purpose (finding books) rather than substituting for buying them.

Software interoperability. Reverse engineering software to create compatible products has been held fair use in several cases, most recently in Google v. Oracle (2021), where Google’s use of Oracle’s Java API declarations in Android was held fair use as transformative reimplementation.

Educational use. A teacher photocopying an article for a one-time classroom discussion is typically fair use. A teacher photocopying an entire textbook for the whole class to avoid buying copies isn’t.

Time shifting and personal use. Recording a TV program to watch later was held fair use in Sony v. Universal (1984), the famous “Betamax” case. Personal-use copies of legitimately-acquired works generally fare well under fair use.

Cases that lost

Some uses that intuitively feel fair turn out not to be.

Sampling without license. Using a recognizable portion of a copyrighted song in your own song, even briefly, has consistently been held infringement when no license was obtained. Bridgeport Music v. Dimension Films (2005) held that any digital sampling required a license, however small. Later cases have softened this slightly but the safe assumption remains: sampling requires clearance.

Whole-work copying for commercial gain. Even when the copy is in a different format, copying the entire work for commercial purposes tends to lose. A wedding videographer who burned full albums of music onto wedding DVDs was held infringing despite arguments about transformative use.

Memes that exceed parody. A meme that doesn’t comment on the underlying work but just uses it as a visual gag, especially one that’s commercialized, has limited fair use protection. The 2020 cases against various commercial meme-merchandising operations went against the defendants.

AI training (current state). The legal landscape for AI training on copyrighted works is in active litigation as of 2026. Several cases (the New York Times v. OpenAI, Getty Images v. Stability AI, and others) are working through courts. The “is AI training fair use” question is genuinely unresolved, with thoughtful arguments on both sides.

Aggregating news articles. Sites that scraped and republished news content with minimal commentary have generally lost fair use defenses, particularly when the practice substituted for visits to the original publishers’ sites.

The boundaries that aren’t bright

A few areas where the law remains genuinely unclear:

How much commentary is enough? If you embed a 5-minute video clip and add 30 seconds of commentary, is that fair use? Courts have come down inconsistently. The trend favors more commentary and shorter excerpts.

Style versus content in visual art. Can you train on an artist’s style and reproduce style-similar new works? Pre-AI cases were almost nonexistent. AI cases are now central to the field.

Educational use in commercial contexts. A university professor using copyrighted material in an online course at a tuition-charging institution. The educational purpose is real. The commercial context complicates the analysis.

Memes and reaction videos. The volume of meme and reaction content vastly exceeds the volume of clear case law about it. Many uses likely qualify as fair use but haven’t been formally tested.

What to do if you’re relying on fair use

Practical advice if you’re making or distributing content that relies on fair use:

Document your reasoning. Before you publish, write down why you believe your use is fair under each of the four factors. If you ever get challenged, this document is your starting position.

Use only what you need. The third factor strongly favors taking the minimum necessary. If 30 seconds of a video makes your point, don’t use 5 minutes.

Add real transformation. Commentary, criticism, parody, or repurposing for a fundamentally different audience are all stronger fair use arguments than “I just wanted to use this.”

Don’t substitute for the original. Your use shouldn’t be a replacement for buying or licensing the original work.

Have a takedown response plan. Even when your use is clearly fair, you’ll likely get takedown notices on automated platforms. Know how to file counter-notices and have your documentation ready.

Consider getting a license when stakes are high. If your fair use case is borderline and the project has real commercial value, paying for a license is sometimes cheaper than the litigation defense, even when you’d probably win.

The honest assessment

Fair use is a real and important defense. It’s also more uncertain than the simple summary suggests. The four-factor test gives judges latitude, and different judges weight the factors differently. Recent Supreme Court decisions have narrowed the doctrine in some commercial contexts.

For working creators, fair use is best understood as a defense that protects clearly transformative, commentary-based, or critical uses of small portions of copyrighted works. It’s not a license to use other people’s material commercially when you feel like it.

When you’re making your own original work, the more important question is the inverse: are you generating material that someone else might claim is theirs? That’s where proving your own authorship becomes the more useful tool than understanding their fair use rights against you.

Fair use protects what you legitimately need to do with others’ work. Copyright registration protects what they legitimately need to do with yours. Both matter. Most creators only think about one of them.