rof. David S. Touretzky, a computer scientist at Carnegie-Mellon University, says he has never watched a movie on DVD, much less copied one illegally. So why is the movie industry calling him a pirate?

The answer can be found on a university site which houses an unusual Web project launched by Professor Touretzky - a project which has turned him into something of a celebrity in Internet legal circles. His site is a gallery devoted to representations of a piece of software that has been deemed illegal because it can be used to break through the copy-protection system on DVD movies.

Last month, Professor Touretzky received an e-mail message from the anti-piracy division of the Motion Picture Association of America, the trade group representing major studios, referring to "unauthorized distribution of copyrighted motion pictures" on the site.

"We have notified your ISP of the unlawful nature of this Web site and have asked for its immediate removal," the message stated.

Professor Touretzky defends the project (www.cs.cmu.edu/~dst/DeCSS/Gallery/), which features submissions from like-minded programmers and academics, saying it grew out of his long-standing interest in free-speech issues.

"It never occurred to me that someone would actually try to prevent people from publishing code that they wrote," he said. "The idea just struck me as so deeply offensive that I felt I had to do something about it."

The code in question was written in 1999 by programmers who wanted to watch their DVDs on computers running the Linux operating system. No legitimate software for doing this existed at the time. Not to be deterred, the programmers found that the encryption scheme protecting the discs was easy to crack, and in the spirit of the open-source software movement, they distributed their new code to others via the Internet.

While Linux users might have rejoiced, the developers of this new so-called DeCSS software ran afoul of the Digital Millennium Copyright Act, a controversial federal law passed in 1998 that makes it illegal to offer a way to gain unauthorized access to a copyrighted work protected by encryption.

In a widely followed case last summer, the movie industry sued Emmanuel Goldstein, the publisher of 2600, a print and Web publication for hackers, in an effort to stop him from posting the software on his site or linking to it on other sites. The judge sided with the studios, saying that the software was an "epidemic" that could destroy the market for home video.

Professor Touretzky testified at the trial after bringing his Web site to the attention of the Electronic Frontier Foundation, which paid for Goldstein's defense. To make his point about free speech, he offered several exhibits from his gallery, including a description of the DeCSS code in plain English and a T-shirt on which the code was printed -- both of which could be considered illegal under the copyright act.

"What I wanted to do was demonstrate that there is no way to draw a line between computer code and other forms of speech that everybody recognizes as protected speech," Professor Touretzky said. "I don't think code should be treated any differently than a recipe or an instruction manual."

He believes that the judge agreed with him, but that the movie industry still won the case because the judge "invented a new category of speech that was not protected, which basically comes down to anything that threatens the profits" of the studios. The judge's decision has been appealed, and hearings are scheduled to start May 1.

Professor Touretzky said that given his involvement with the DeCSS case, the form letter he received last month from the MPAA about his site was probably a mistake. It did, however, provide "an opportunity to embarrass them," he said.

In his response to the MPAA, Professor Touretzky asked it to specify which of the several dozen forms of the software on the site it objected to, and to provide a legal basis for that objection. He also noted that the site was by now a "well-known academic work," and asked whether the movie industry was seeking to "exert editorial control over scholarly publications by computer science faculty that deal with DeCSS."

Earlier this month the MPAA acknowledged Professor Touretzky's response and said it would "consider it and respond appropriately at the proper time."

This does not mean that Professor Touretzky is off the hook. Mark Litvack, vice president and legal director for anti-piracy at the MPAA, questioned whether there was a legal difference between posting the software for academic purposes and posting it to allow others to copy DVDs.

"When you post it for the world to see and for the world to take, you can't control how it's used," he said.

Litvack noted that a professor who posted child pornography in the context of a class on policing Internet crime would still be breaking the law.

"You're not allowed to traffic in it, period," he said. "It's illegal material."

But Litvack said the MPAA would not necessarily be concerned about some of the exhibits in Professor Touretzky's gallery, like the T-shirt or the recording of someone singing the computer code with a guitar accompaniment, because these are not "circumvention devices" as defined by the law.

"What the MPAA is concerned with is that there are devices that are used to decrypt our movies," he said. "Your T-shirt cannot do that. It's not a device that, by itself, does anything."

So what representations of the DeCSS code would upset the MPAA? Litvack said that the question of where to draw the line is "something we will look at and the courts will look at."

Meanwhile the gallery continues to grow. Programmers have been competing to come up with the shortest possible code for descrambling DVD encryption. The record-holder is now just 434 bytes long, small enough to fit on a business card. And this month a programmer in Finland with a penchant for math came up with a way to hide the DeCSS code in the digits of a very long prime number, making it perhaps the first such number that is illegal.

Watching or copying a DVD using the code on the gallery site would require a fair amount of technical knowledge. But Professor Touretzky said he had heard of new software that makes it easy for anyone to turn a DVD movie into a file on a hard disk, similar to the way CDs can be "ripped" to make MP3 files. He said he would probably not post such software on his site.

"I'm more interested in the speech issues than in pirating DVDs," Professor Touretzky said. Even though such software would still be a form of speech, he said, "I'm also really interested in not getting sued. If they're going to sue me, I'm going to make it hard for them."