Napster's courtroom battle might have been the week's big drama, but it wasn't the only digital-media melee to go down. On Tuesday in a federal courtroom in New York, the defense rested in the suit brought by eight major movie studios against hacker/journalist Eric Corley. The studios are trying to block DeCSS, a DVD decryption program; Corley published a link to the offending code on his Web site, 2600.com. Appeals are inevitable, no matter which way Judge Lewis A. Kaplan decides, but here's a picture of the arguments, the possible outcomes and their implications.

For the prosecution: Originally written to provide Linux users a way to watch DVDs, DeCSS skirts the studios' encryption programs. The studios argue that DeCSS threatens irreparable harm to their copyrighted material, and is nothing more than a utility for piracy. Look no further, they say, than the Digital Millennium Copyright Act of 1998, which specifically forbids the circumvention of copyright protection schemes.

The studios' reading of the DMCA would prohibit the spread of DeCSS code in any form. No Web site, including those run by journalists and news organizations, could provide links to sites that post the decryption utility.

But the precedent wouldn't stop at DVDs, defense experts warned. Computer code, testified David Touretzky, an artificial intelligence researcher at Carnegie Mellon University, is a language, plain and simple. "My theories are expressed as computer programs," he said. Touretzky argued that if computer code is not afforded full First Amendment protection, "anyone who publishes a computer program is at risk." Judge Kaplan called that argument "persuasive."

For the defense: "Nobody's in court arguing for the right to copy movies," says Wendy Seltzer, a fellow at Harvard University's Berkman Center for Internet and Society and a Corley supporter. "The defense is arguing for the right to view movies on a different platform, a platform of their choice, and the right to use an excerpt in an academic presentation." If Judge Kaplan agrees, use of DeCSS will simply fall under the "fair use" interpretation of the copyright act.

The studios paint a more dire picture: If DeCSS (or programs akin to it) proliferates, it would cost them millions in lost revenue. But that's not a sure thing. Movie files are so large and bandwidth so taxed that films can take hours to download. It's still far easier to rent a DVD for three bucks. That may be one reason why the prosecution hasn't come up with an example of widespread DeCSS piracy.

The rub of the case is that, unlike Napster, there's no one place to get DeCSS. Hundreds of thousands of copies of DeCSS software exist on Web sites and hard drives, meaning any injunction will be almost impossible to enforce. As Judge Kaplan notes, "This horse is out of the barn."