Legal pundits regard David Boies as the digital era's Clarence Darrow, a go-for-the-jugular charmer who could explain HTML to a Neanderthal.

Mr. Boies was, of course, on Al Gore's speed-dial during the post-election fracas. And as the Justice Department's ace litigator in the Microsoft antitrust trial, Boies earned legend status by eviscerating Bill Gates in a pretrial deposition. So when Napster enlisted Boies to fend off a copyright-infringement suit, cyberlibertarians hailed him as the savior who would preserve unfettered access to gratis Jay-Z tunes. No one guessed he'd botch the case.

Granted, Napster -- which may be shut down in light of a Monday appeals-court ruling -- always faced long odds. The recording industry is sexy, rich, and powerful, and its victimized poster children -- struggling musicians deprived of royalties -- are far more sympathetic than whiny college students hooked on sonic freebies. Napster glimpsed the handwriting on the wall last October, when it created a pay-for-play service in tandem with German conglomerate Bertelsmann AG.

Yet Boies sealed his client's future by relying on an arcane argument that couldn't quite pass the laugh test. He compared Napster's file-sharing service to a VCR, invoking a 1984 case, Sony Corporation v. Universal City Studios Inc., which OK'd the taping of copyrighted TV shows for personal use. The ruling maintained that a device cannot be outlawed if a preponderance of its uses is legitimate. Since Napster can theoretically be used to swap non-copyrighted files, Boies contended, then his client shouldn't be held responsible for the copyright-shirking activities of a few miscreants.

The federal Court of Appeals for the Ninth Circuit could see through that whopper. Sony could credibly claim ignorance of its rogue customers' intentions, since it merely shipped the hardware; no Sony employee could physically witness a VCR owner secretly taping "Dynasty" episodes. A Napster executive, on the other hand, need simply flick on his computer to realize that the service's raison d'etre is the swiping of major-label property.

Courts tend to look unfavorably upon willful blindness of that magnitude. Instead of lamely pleading ignorance and impotence, Boies should have attacked the core tenet of the plaintiffs' case -- that a song downloaded from Napster is identical to a song on a retail CD. This is one of the recording industry's favorite myths, a convenient oversimplification of digital technology.

Napster's songs are downloaded as MP3 files, a format that drastically compresses the original's digital information. Laid out on paper, the binary code for an MP3 version of the latest Limp Bizkit cut would appear radically different from the binary code for the album version.

Even a trained eye would be unable to detect similarities between each printout's string of ones and zeros, the "building blocks" of digital code. This code alteration provides Napster with an as-yet-untested loophole.

If the files its users exchange are not, in fact, flawless clones of the files produced by record labels, then Boies could argue that non-commercial copying is directly analogous to xeroxing magazine articles -- the content is degraded, but intact. He could have summoned a bevy of audiophiles to attest to the format's inferior quality, its tendency to dull the richness of bass and treble tones. At the very least, highlighting the physical differences would have helped Boies elucidate his fair-use argument.

Blinded by the recording industry's digital-information myth, the court failed to recognize the parallel between downloading MP3s and taping songs off the radio, a practice protected under the federal Audio Home Recording Act. An explanation of the code-alteration principle would have strengthened the validity of that comparison.

The code argument would also have bolstered Boies's tepid attempts to prove Napster's benign nature. A key element of the Ninth Circuit's ruling was its affirmation that Napster's existence threatened the recording industry's bottom line. If Boies had demonstrated that MP3s are substantively different from the digital files contained on retail CDs, he could have implied that the service was not in direct competition with brick-and-mortar outlets. This theory is borne out by current CD sales, robust in spite of Napster's 57 million users.

Napster may be facing extinction, but it still has an outside shot at survival. If the company has the moxie to last a few more months, an appeal to the fully assembled Ninth Circuit could stave off oblivion. In preparing for that showdown, Boies would be well advised to adopt the code stratagem.