Written & reviewed by NotALawyer Review AI · Updated June 26, 2026
Fair use is a part of copyright law that lets you use a copyrighted work without permission in certain situations — like commentary, criticism, news reporting, teaching, or parody. But it isn't a blanket permission slip. It's a legal defense that gets decided case by case, by weighing four factors. There's no bright-line rule that makes any particular use automatically safe.
Under federal law, a fair-use question turns on four things: the purpose of your use (is it transformative, commercial, or for nonprofit education?), the nature of the original work, how much of it you used, and the effect on the market for the original. No single factor decides it — a judge balances all four.
Using a work to do something new — adding commentary, criticism, or a different meaning — leans toward fair use. Copying a work to serve the same purpose it already served, like reposting a photo to illustrate the same kind of story, leans against it.
Giving credit is good practice, but it does not make a use fair. Copyright is about permission and the four factors, not attribution. You can name the source and still infringe; plenty of takedown disputes involve fully-credited reposts.
There's no magic number of seconds, words, or bars of music that's automatically safe. Courts have found short clips infringing and longer excerpts fair — it depends on the four factors, including whether you took 'the heart' of the work. The amount that's reasonable varies with the situation.
Imagine a reviewer who shows brief clips while critiquing the directing and acting. The commentary is transformative, the clips are short, and the review isn't a substitute for watching the movie — all factors that tend to favor fair use. Swap in the whole film with no commentary and the analysis flips the other way. Same channel, very different outcome.
Because it's decided case by case, you usually only find out whether a use was fair if a dispute reaches a judge. If you've received a cease-and-desist or takedown notice and you believe your use is lawful, that's the moment to talk to a licensed attorney in your state about how the four factors apply to your specific facts.
More on this topic: the Cease & Desist hub
NotALawyer.com provides general legal information, not legal advice.