The original infringement claim was made by
, a firm founded by a former University of California professor that had alleged the software giant used technology at the school in its Internet Explorer software,
The Wall Street Journal
The case has been remanded to the District Court.
Microsoft, which had said Eolas' patent was not valid, called the appeals court ruling "a clear victory not only for Microsoft, but for Internet users as well."
A federal jury had ordered Microsoft in 2003 to pay about $520 million to Eolas and the University of California, which jointly sued the software company for infringement. The patent covers a method for interactive content to be embedded in a Web page,