In court filings this week in Duluth, Minn. the record labels argue that making music tracks available on peer-to-peer networks like Kazaa in itself constitutes copyright infringement. Otherwise, the record companies argue, they would not be able to protect themselves from piracy. "Millions of people use services like Kazaa to make copyrighted works available for illegal downloading," the record labels argue. "Copyright owners typically have no way to monitor--much less prove--the actual transfer of those files."

At trial last year, federal district court judge Michael Davis of Duluth, Minn. instructed the jurors that they could find Thomas liable if she had made tracks available for uploading. They ruled against her and ordered the single mother to pay $220,000 in damages.

But Davis had second thoughts in May and asked the parties to submit briefs about the issue. If he decides that he wrongly instructed the jury, he could order a new trial in the case.

Since the Thomas case went to the jury, other federal courts have come to different conclusions about whether making tracks available on a peer-to-peer network constitutes copyright infringement. Federal judge Neil Wake in Arizona ruled that making tracks available was not in itself enough to prove copyright infringement. But a federal judge in New York decided that simply offering tracks can potentially violate a copyright holder's rights.

In the Thomas case, the record labels argue that even if Davis wrongly instructed the jury about the law, a new trial is not warranted because their investigator, MediaSentry, downloaded specific files from Thomas's Kazaa folder. Therefore, they argue, Thomas did more than just make tracks available; she distributed them.

But Thomas argues that downloads by the record labels' agent cannot constitute copyright infringement because the labels have authorized that distribution.

"In this case, the only evidence of a distribution was the copying of 26 songs by plaintiffs' agents... (An) agent cannot infringe the copyright owner's rights when acting on the owner's behalf," Thomas's lawyer argued in a brief filed this week.

Thomas also argues that the court should not have told the jurors they could equate making tracks available with infringement.

The case has drawn significant attention by digital rights advocates as well as media executives. Digital rights groups including the Electronic Frontier Foundation and Public Knowledge filed papers on behalf of Thomas. They argue that equating making files available with distribution will broaden copyright law in a way that could harm many Web companies. "An inappropriately expansive reading of the distribution right will have far-reaching effects on the rights of users of digital works as well as the ability of innovators to find new, legal uses for those works," they wrote.

The Motion Picture Association of America weighed in on behalf of the record industry. Much like the record labels, the film industry argued that the advent of digital technology makes it hard to find "direct proof" of copyright infringement.

For the record industry, the stakes are particularly high because industry executives view copyright enforcement as crucial to ending online piracy and reversing a slide in revenue. Last year, revenue totaled $10 billion--down from approximately $15 billion in 2000, when the original Napster was introduced. Since 2003, the Recording Industry Association of America has sued or threatened to sue 26,000 people as part of its campaign against copyright infringement.

Davis is expected to hold a hearing in the case on Aug. 4.