IBM has filed new documents in its legal dispute with Unix vendor The SCO Group, accusing SCO of having no evidence to back up its copyright infringement claims, and asking the judge to throw a major component of the case out of court.

"For more than a year, SCO has made far-reaching claims about its right to preclude IBM's (and everyone else's) Linux activities," said IBM. "Despite SCO's grandiose descriptions of its alleged evidence of IBM's infringement, SCO now effectively concedes that it has none."

SCO has been unable to provide any evidence of copyright infringement during the discovery phase of the trial and the court should therefore render a summary judgement against SCO, IBM's filings say.

In March 2003, SCO filed a multibillion dollar lawsuit against IBM, accusing it of violating SCO's Unix intellectual property. SCO accused IBM of unfair competition, breach of contract, and of violating SCO's trade secrets. In late February 2004, it dropped the trade secret allegations in the case, but added a claim that IBM had violated SCO's Unix copyright.

A few weeks after the trade secret claims were dropped, IBM sought a declaratory judgement in the case, a move that opened the possibility of a quick ruling against SCO. Lawyers following the dispute saw this as a sign of growing confidence on IBM's part.

By seeking a declaratory judgement, IBM was showing that it had not found any evidence to back up SCO's claims, said Jeff Norman, an intellectual property lawyer. Because the copyright claims form the crux of SCO's case, this week's filing for a summary judgement creates the possibility that the dispute could essentially be over in a matter of months, he said.

"IBM is saying (to SCO), 'As a matter of law you're playing this so weak that no reasonable jury could find in your favor,'" Norman said. "They must think that they have a pretty good chance of winning the motion, or you wouldn't bring it."

This week's filings could also force SCO to provide more compelling evidence of copyright violations, said patent lawyer David Byer. "It is another way to try to focus the court on the evidentiary questions that have been battled about since day one, meaning who is going to produce what when," he said. "SCO needs to respond to this. If they don't respond appropriately, the case can get thrown out."

SCO is likely to produce more evidence to support its claims, said Blake Stowell, an SCO spokesman. On April 19, IBM turned over 232 versions of its AIX and Dynix Unix source code as well as internal documents and memos from executives, he said.

"Our lawyers are still going through much of the evidence IBM turned over as part of the discovery process. I'm confident that there is still other evidence that will come forward on order for us to be able to prove those claims," Stowell said.

Complicating matters for SCO is the fact that Linux vendor Novell Inc. also claims to own copyright to the Unix source code. SCO has sued Novell for slander in connection with this claim.