The Recording Industry Association's case against Napster comes to the US District Court on Friday. The RIAA will try to prove Napster is complicit in breaking US copyright law. The controversial music swapping software company will try to persuade the court that it's no such thing.

It has to be said, though, that the balance isn't in Napster's favour. District Court Judge Marilyn Patel has already granted the RIAA a temporary injunction against Napster. The appeals court overturned that judgement on the grounds that the case was a precedent-setting one - "issues of first impression", in legal speak.

The reason for such an appeal judgement? "One of the reasons that you have appellate courts is to guard against the chance that a district court makes an inadvertent error of law or misreads the facts," Napster lawyer David 'Microsoft antitrust suit' Boies told Reuters.

The judgement allowed Napster to continue operating, but brought forward the main RIAA case to 18 August - this coming Friday.

The RIAA is confident that Judge Patel will maintain her stance and come down on the side of the music industry. Boies' plan is to convince her otherwise with a better explanation of the technology behind Napster's MP3 sharing software.

"One of the problems that may have existed on the district court level was... they declined to grant our request for an evidentiary hearing. We may not have done as good a job as we would have been able to in explaining the facts and the technology, said Boies. "When we go back to the district court we have to do a better job in explaining the technology."

Once again, Boies will argue that Napster's file sharing software simply allows music owners to give music to their friends, on a non-commercial basis, and is thus working well within the US Home Recordings Act (HRA).

The RIAA will claim that the HRA's provision caters only for a listener's immediate family, not complete strangers, and that since Napster's business (such as it is) is built on capitalising upon all this sharing activity, that voids Napster's 'it isn't commercial' argument.

The appeal court's ruling will ensure Judge Patel weighs up these issues again, but it's hard to imagine she will change her stance in Napster's favour. ®

Check out our full coverage of the Napster controversy