Today, seventeen computer science professors (including me) are filing an amicus brief with the Supreme Court in the Grokster case. Here is the summary of our argument, quoted from the brief:

Amici write to call to the Court’s attention several computer science issues raised by Petitioners [i.e., the movie and music companies] and amici who filed concurrent with Petitioners, and to correct certain of their technical assertions. First, the United States’ description of the Internet’s design is wrong. P2P networks are not new developments in network design, but rather the design on which the Internet itself is based. Second, a P2P network design, where the work is done by the end user’s machine, is preferable to a design which forces work (such as filtering) to be done within the network, because a P2P design can be robust and efficient. Third, because of the difficulty in designing distributed networks, advances in P2P network design – including BitTorrent and Respondents’ [i.e., Grokster’s and Streamcast’s] software – are crucial to developing the next generation of P2P networks, such as the NSF-funded IRIS Project. Fourth, Petitioners’ assertion that filtering software will work fails to consider that users cannot be forced to install the filter, filtering software is unproven or that users will find other ways to defeat the filter. Finally, while Petitioners state that infringers’ anonymity makes legal action difficult, the truth is that Petitioners can obtain IP addresses easily and have filed lawsuits against more than 8,400 alleged infringers. Because Petitioners seek a remedy that will hobble advances in technology, while they have other means to obtain relief for infringement, amici ask the Court to affirm the judgment below.

The seventeen computer science professors are Harold Abelson (MIT), Thomas Anderson (U. Washington), Andrew W. Appel (Princeton), Steven M. Bellovin (Columbia), Dan Boneh (Stanford), David Clark (MIT), David J. Farber (CMU), Joan Feigenbaum (Yale), Edward W. Felten (Princeton), Robert Harper (CMU), M. Frans Kaashoek (MIT), Brian Kernighan (Princeton), Jennifer Rexford (Princeton), John C. Reynolds (CMU), Aviel D. Rubin (Johns Hopkins), Eugene H. Spafford (Purdue), and David S. Touretzky (CMU).

Thanks to our counsel, Jim Tyre and Vicky Hall, for their work in turning a set of ideas and chunks of rough text into a coherent brief.

I’m on the road today, so I don’t have a long post for you. (Good news: I’m in Rome. Bad news: It’s Rome, New York.)

Instead, let me point you to an interesting exchange about copyright and ad-blocking software on my course blog, in which “Archer” opens with a discussion of copyright and advertising revenue, and Harlan Yu responds by asking whether distributing Firefox AdBlock is a contributory infringement.

There’s plenty of interesting writing on the course blog. Check it out!

UPDATE (Feb. 28): Another student, “Unsuspecting Innocent,” has more on this topic.

Christin, Weigend, and Chuang have an interesting new paper on corruption of files in P2P networks. Some files are corrupted accidentally (they call this “pollution”), and some might be corrupted deliberately (“poisoning”) by copyright owners or their agents. The paper measures the availability of popular, infringing files on the eDonkey, Overnet, Gnutella, and FastTrack networks, and simulates the effect of different pollution strategies that might be used.

The paper studied a few popular files for which corruption efforts were not occurring (or at least not succeeding). Polluted versions of these files are found, especially on FastTrack, but these aren’t a barrier to user access because non-corrupted files tend to have more replicas available than polluted files do, and the systems return files with more replicas first.

They move on to simulate the effect of various pollution strategies. They conclude that a sufficiently sophisticated pollution strategy, which injects different decoy versions of a file at different times, and injects many replicas of the same decoy at the same time, would significantly reduce user access to targeted files.

Some P2P programs use simple reputation systems to try to distinguish corrupted files from non-corrupted ones; the paper argues that these will be ineffective against their best pollution strategy. But they also note that better reputation systems could can detect their sophisticated poisoning strategy.

They don’t say anything more about the arms race between reputation technologies and pollution technologies. My guess is that in the long run reputation systems will win, and poisoning strategies will lose their viability. In the meantime, though, it looks like copyright owners have much to gain from poisoning.

[UPDATE (6:45 PM): I changed the second paragraph to eliminate an error that was caused by my misreading of the paper. Originally I said, incorrectly, that the study found little if any evidence of pollution for the files they studied. In fact, they chose those files because they were not subject to pollution. Thanks to Cypherpunk, Joe Hall, and Nicolas Christin for pointing out my error.]

This afternoon I’m going to lead a discussion among twenty-five bright Princeton students, about the basics of copyright. Why do we have copyright? Why does it cover expression and not ideas? Why fair use? The answers are subtle, but I hope to guide the discussion toward finding them.

I can say for sure that a flat “downloading = shoplifting” argument would be torn to shreds in minutes. This equation seems wrong to most people, and it is wrong. Copyrights differ from traditional property in important ways. That doesn’t mean that copyright isn’t justified, but it does mean that the justification for copyright doesn’t follow from the justification for ordinary property. It will take a room full of college students a while to sort through all of this.

Let’s face it, this is challenging material, even for smart, motivated twenty-year-olds.

Meanwhile, JD Lasica notes that in fourth-grade classrooms, the BSA’s anticopying ferret (who seems, amusingly, to have been copied himself) will try to explain the same concepts to nine-year-olds. Cory Doctorow observes that this is crazy. Telling nine-year-olds that they have to understand copyright before they can use the Internet is like telling them that they have to understand employment taxes before they can run a lemonade stand.

I pity the fourth-grade teacher who, having read the BSA’s Teacher’s Guide, has to explain exactly what it is that is being stolen when a kid copies an image from the Barbie website to use as a placemat at dinner. If I were that teacher, I would prefer simpler questions like “Why are people mean to each other?” and “How did the universe start?”