A Chicago federal judge on Wednesday upheld a $512 million patent verdict against Microsoft that could ultimately force major changes in many of the most common Internet software products.

Judge James Zagel said he saw no reason to overturn an August jury verdict that said Microsoft's Internet Explorer Web browsing software had infringed on patent rights held jointly by small developer Eolas Technologies and the University of California.

As part of his decision, Zagel barred Microsoft from distributing versions of its Web software that include the potentially infringing technology. However, he immediately put that injunction on hold until an appeal has run its course. Microsoft is expected to appeal immediately.

"This motion rehearses a set of arguments that failed the first time around," Zagel wrote in his opinion. "While I am not entirely comfortable with the large size of the judgment, it is not my comfort that matters."

The August ruling set off a mild panic in the Web developer community, which fears it may have to change the way that many basic Web page functions are created or triggered if Eolas is ultimately victorious in its suit.

The Eolas patent covers technology used to call up separate applications, such as a media player or document viewer, within a Web page.

Web programmers have spent much of the past several months scouring programming history to find what is called "prior art," or evidence that other people had invented the technology before Eolas, in order to try to invalidate the patent. The U.S. Patent and Trademark Office has opened a rare hearing to investigate the validity of the patent.

Microsoft has said that it believes that the Eolas patent will ultimately be found invalid, either by the courts or by the U.S. Patent and Trademark Office. It has already released versions of IE that try to sidestep some of the patent's claims, and has advised other Web developers to do the same.

"We remain confident that on appeal, when people hear this though, they will see that--as we claimed--the patent is not valid," Microsoft spokesman Lou Gellers said. "We don't think we violated anything even if it were valid."

Marty Lueck, an attorney for Eolas, applauded the ruling, in part because it would move the process to the appeals court more quickly.

"This forces the appeal process to begin and brings us another step closer to full resolution of case, which we would welcome," Lueck said. "Microsoft is a difficult opponent."

Eolas founder Michael Doyle said that the company would be happy to settle, but that Microsoft has not responded to Eolas' overtures.

The software giant has 30 days to file a notice of appeal in the case. As part of his ruling, Zagel said Microsoft must pay more than $45 million in "prejudgment interest" for the infringement while the appeal is mounted.

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