U.S. District Judge Marilyn Hall Patel also appointed an expert to review the documents, which officials for the recording industry's trade group say they are ready to provide.
The record labels are seeking damages from the once-popular online file-sharing network for allowing the copyright songs to be trafficked.
The judge also opened the door to legal discovery on Napster's claims that the labels misused their copyrights to dominate the growing online music distribution industry.
Napster said both rulings were significant victories for the embattled company, which has been offline since July.
"We are pleased that the court granted Napster's request to examine two critical issues: the record companies' ownership of artists' copyrights and anticompetitive behavior that amounts to misuse of their copyrights," Napster general counsel Jonathan Schwartz said in a statement.
Cary Sherman, general counsel for the Recording Industry Association of America said Napsters allegations of misuse are without merit, which will be confirmed through the ordered discovery.
"We look forward to providing the court with evidence to refute Napster's claims," Sherman said in a statement.
By RON HARRIS