The appeal, filed on Thursday, relates to limitations placed on the extent of prior art evidence that the District Court allowed Microsoft to put forward to support its claim that the technology behind the Eolas patent was already in the public domain and that the patent was therefore invalid.
Microsoft has asked the court to reverse the infringement ruling, or to declare a mistrial, according to a CNET News.com report. The software giant has also petitioned the court to include only the US sales of Windows in the calculations relating to the fine imposed on the company.
Background
The dispute dates back to 1999, when Microsoft was sued by the University of California and Eolas Technologies over allegations that Microsoft's Internet Explorer program infringed a patent for a method that allows web browsers to access interactive application programs.
In August last year a jury agreed with the claim and awarded damages of $520.6 million plus interest to Eolas. This verdict was upheld in January and a Chicago District Court imposed an injunction on the software firm, banning it from distributing the infringing software.
The ban was stayed pending an appeal – now filed by Microsoft.
In separate proceedings, the US Patent and Trademark Office agreed in November to re-examine the Eolas patent and in March issued a preliminary ruling that the patent was indeed invalid. This followed written evidence of prior art being brought to its attention that raised what the Patent Office described as "a substantial new question of patentability" - the legal basis for any form of re-examination.
Eolas filed a response to that finding only a few weeks ago but a definitive decision from the USPTO could take years, according to commentators.