The SCO Group has accused IBM of misrepresenting its case against the giant and failing to provide adequate information during the legal discovery process.
The claims came in the company's written arguments to the judge in the case following IBM's request for the whole case to be dismissed due to lack of evidence.
A summary judgment would be premature, SCO also argued, since it has acted in good faith and has not yet had the opportunity to make full discovery.
If granted the request for summary judgement, it would essentially put an end to the matter, say legal experts. Big Blue has also asked the court for a declaratory judgment on the question of whether IBM violated SCO's copyright, which would prevent new copyright claims from being brought against IBM at a later date.
Though SCO has asserted that Linux contains code copied line for line from its Unix System V source code, the Thursday filings indicate that SCO does not believe that IBM was responsible for these alleged violations.
"SCO has not alleged any copyright violation based on IBM's contributions to Linux," the filings state. The only copyright claim SCO has brought against IBM has to do with the AIX and Dynix operating systems, which IBM continued to distribute after SCO "terminated" IBM's Unix licenses last year, the filings state.
SCO fought back: "No matter how many times IBM mischaracterises it, this case is not about literal copying of Unix source code into Linux. Instead, SCO has claimed from the very outset that IBM's contribution to Linux of the resulting materials" it created as modifications to or derivative works based on Unix System V constitutes a breach of IBM's licensing agreements."
Because SCO's public statements about alleged copyright infringement in Linux have been stronger than those in its court filings, the question of whether the SCO/IBM case is simply a contract dispute between the two companies or a copyright case - which could create greater liabilities for users - has been obscured, said Jonathan Eunice, an analyst with Illuminata.
"It's a squishy case," Eunice said. "There was this whole period of multiple months where SCO was essentially saying there is line-for-line copying, ergo it's a clear-cut copyright case for us. If you talked to SCO's lawyers, they treated the copyright case as more of an indication than the real case they wanted to bring. I believe that they want to broaden out the case [to include more copyright claims]," he said.
IBM and SCO will have an opportunity to argue their positions on the summary judgment question on 4 August, when the court hears oral arguments on the matter, said Blake Stowell, an SCO spokesman.