The SCO Group's crusade to be recognised as part-owner of open-source OS Linux has been dealt yet another blow after a Michigan judge effectively threw out its entire case against auto giant DaimlerChrysler.

A spokeswoman for the car company welcomed the decision: "We are pleased with the judge's ruling and we look forward to finally resolving the one open issue."

SCO filed the lawsuit in March, claiming that DaimlerChrysler had refused to provide a "certification of compliance" showing that it had continued to abide by a Unix licensing agreement from November 1990.DaimlerChrysler responded in April, asking the court to dismiss the lawsuit and claiming that there was "no genuine issue of material fact" in SCO's case.

The automaker included two letters in its April filings. One letter certified that DaimlerChrysler no longer uses the software licensed under the 1990 agreement. The second, addressed to SCO, argued that SCO had no right to seek such certification, but said that the first letter "should cause SCO to dismiss its suit".

The one "open issue" remaining in the lawsuit is whether SCO suffered damages as a result of receiving the certification letter in April rather than in January, Gauthier said.

The letters were received by SCO only after a 30-day deadline for certification had passed, according to an SCO spokesman: "When their deadline for certifying passed without any response, we assumed that they had not certified because they could not certify," he said. "It’s unfortunate that, only after we filed litigation against them, they finally decided to certify their compliance."

But responding to SCO's original letter within 30 days might have been difficult. The letter, sent in December, was sent to Chrysler's former corporate headquarters in Highland Park, Michigan, according to DaimlerChrysler's court filings. "DaimlerChrysler headquarters moved out of Highland Park several years ago," said Gauthier.

While Stowell declined to say whether SCO now plans to drop the case, it seems unlikely that it would have much success seeking damages for the four-month delay in delivery of the certification letter, said Jeff Norman, an intellectual property partner with the Chicago law firm Kirkland Ellis. "Unless they amend the complaint or somehow overturn the judge's ruling, I don't think it makes any sense to pursue," he said.

SCO could keep the case alive by adding new claims to its complaint or by asking the judge to reconsider his decision, Norman said. SCO will now consider its options for any next steps, but the case will have no impact on its ongoing litigation with IBM, Novell or AutoZone, an SCO spokesman said.

"The biggest mistake that anyone can make with today's ruling is to assume that the thing that happened today with DaimlerChrysler will have some sort of impact on our AutoZone or Novell or IBM cases," he said.