The US Supreme Court has decided not to hear a Microsoft appeal in the ongoing Web browsing patent dispute with the University of California and Eolas Technologies.

Microsoft suffered a $520.6 million judgement in the case two years ago, but appealed it on several fronts.

With Monday's decision, the Supreme Court has decided not to hear Microsoft's appeal relating to how damages in the case should be calculated.

Microsoft had been asking the Court to reject a previous ruling that damages should be awarded based on Microsoft's US and foreign sales, saying that the Eolas patent should only apply to US products.

The Supreme Court gave no reason for its rejection of Microsoft's appeal.

Now the case's focus shifts to the District Court in Chicago, which is examining the validity of the Eolas patent. An appeals court remanded the case to the Chicago court last March, following a Microsoft appeal.

This patent question is the last major decision before the courts, said Trey Davis, a University of California spokesman: "There's not an outstanding question now of infringement or damages," he said. "There's just a question of whether the patent is valid or not."

"We will continue with the trial of the remanded case before the District Court and we're confident that our position will ultimately prevail," said Jack Evans, a Microsoft spokesman.

In September, the US Patent and Trademark Office finished a re-examination of the Eolas patent, declaring it to be valid.

This legal dispute has been in play since 1999, when Eolas sued Microsoft, claiming that technology within Internet Explorer violated a 1998 University of California patent developed by Eolas founder Michael Doyle.

Eolas has exclusive rights to use and license the patent, which describes, in part, "a system allowing a user of a browser program to access and execute an embedded program object."