But if you look a little further back, you’ll see that for a long time now, copyright holders have made a series of concerted efforts to extend copyright protection and make it an ever-more powerful instrument of control.

More than a century ago, copyrights lasted for 14 years  and could be extended another 14 if the copyright holder petitioned for an extension. Today, corporate copyrights last for 95 years, while individuals retain copyrights for 70 years after their deaths. The most recent extension of copyright, passed by Congress in 1998, was nicknamed the Mickey Mouse Protection Act, because Disney’s lobbyists were intent on keeping Mickey Mouse from falling into the public domain  and on preserving billions in profits for Disney.

Image The author J. K. Rowling is suing to stop publication of a Harry Potter companion book. Credit... Ric Francis/Associated Press

At the same time, though, copyright holders have tried to impose rules on the rest of us  through threats and litigation  that were never intended to be part of copyright law. They sue to prevent rappers from taking samples of copyrighted songs to create their own music. Authors’ estates try to deprive scholars of their ability to reprint parts of books or articles because they disapprove of the scholar’s point of view. Mr. Lessig likes to cite a recent, absurd case where a mother posted a video of her baby dancing to Prince’s song “Let’s Go Crazy” on YouTube  and Universal Music promptly demanded that YouTube remove the video because it violated the copyright. Have these efforts had  as we like to say in the news business  a chilling effect? You bet they have.

About a decade ago, Mr. Lessig decided to fight back. His core belief is that copyright protection, as he put it to me, “was meant to foster creativity, not to stifle it”  yet that is how it is now being used. He fought the Mickey Mouse Preservation Act all the way to the Supreme Court (he lost). He founded Creative Commons, which is, in a sense, an alternative form of copyright, allowing creators to grant far more rights to others than the traditional copyright system. And he started the Fair Use Project to push back against copyright hogs like J. K. Rowling.

No one is saying that anyone can simply steal the work of others. But the law absolutely allows anyone to create something new based on someone else’s art. This is something the Internet has made dramatically easier  which is part of the reason we’re all so much more aware of copyright than we used to be. But it has long been true for writers, filmmakers and other artists. That’s what “fair use” means.

And that is what is being forgotten as copyright holders try to tighten their grip. Documentary-film makers feel this particularly acutely. My friend Alex Gibney, who directed the recent film “Taxi to the Dark Side,” about torture, tried to get Fox to license him a short clip from the television series “24” to illustrate a point one of his talking heads was making about how the show glamorized torture. Fox denied his request. Mr. Gibney, a fair-use absolutist, used it anyway  but many filmmakers would have backed away.