The interminable saga of the Eolas patent case is in the news again. TechNewsWorld reports that the U.S. Patent and Trademark Office last week reviewed and reaffirmed a patent owned by the University of California and licensed exclusively to Eolas Technologies; that decision is potentially a serious blow to Internet Explorer and Microsoft, which has been arguing in court that IE does not infringe on the Eolas patent because that patent is invalid (it cites "prior art").

If it loses in court, Microsoft would either have to redesign IE or reach a licensing agreement with Eolas.

The standard for invalidating a patent is clear and convincing evidence that prior art is within the scope of a patent's claims. Since the USPTO validated the Eolas patent, that argument would be difficult to use in court. The Eolas patent, known as the 906 patent after its official number, 5,838,906, covers a method used to call up rich media within a browser.

After several rounds in court (see prior coverage, below), Microsoft must now prove that the Eolas patent is invalid; it is arguing that Eolas knew about a browser called Viola - which constitutes prior art - but did not mention it when first applying for its patent.

Prior coverage:

- Patent Shenanigans Cloud Certainty in Online Ad, Commerce Spaces
- Eolas Trial Judge Faulted in Appeal
- Eolas Case Rears Head Again
- Eolas Rich Media Patent on Way to Grave
- Eolas Case Not Dead Yet
- Eolas Patent Nixed, Microsoft Mostly Off Hook
- Microsoft Still on Patent Hook for $565 Million
- Patent Office Unsure on Eolas Patent
- Microsoft May Yet Win Eolas Case, Advertisers May Yet Lose
- W3C Backs Microsoft Against Submarine Patent
- Motion Filed to Nix IE Distribution
- IE Patent Infringement to Cost MS $521 Million