Judge Richard Posner is guest blogging this week on Lawrence Lessig's blog. There's lots of good discussion going on, but I'd particularly point out the Judge Posner's comments on fair use, which judging by a couple of discussions I've been involved in recently, many people misunderstand (at least in part because many copyright holders overclaim copyright).

For example, in a post entitled 'Fair Use and Misuse'

Here is a very worrisome problem concerning fair use. It has to do with a dichotomy long noted by legal thinkers between the law on the books and the law in action. They often diverge. And fair use is an example of this divergence. As I said in an earlier posting, fair use often benefits rather than harms the copyright holder. However, it doesn't always; moreover, even if a copyright holder is not going to lose, and is even going to gain, sales from a degree of unlicensed copying, if he thinks he can extract a license fee, he'll want to claim that the copying is not fair use; and finally, because the doctrine has vague contours, copyright owners are inclined to interpret it very narrowly, lest it expand by increments.

The result is a systematic overclaiming of copyright, resulting in a misunderstanding of copyright's breadth. Look at the copyright page in virtually any book, or the copyright notice at the beginning of a DVD or VHS film recording. The notice will almost always state that no part of the work can be reproduced without the publisher's (or movie studio's) permission. This is a flat denial of fair use. The reader or viewer who thumbs his nose at the copyright notice risks receiving a threatening letter from the copyright owner. He doesn't know whether he will be sued, and because the fair use doctrine is , he may not be altogether confident about the outcome of the suit.

There's lots of other good stuff, too.