Microsoft late on Tuesday filed its formal appeal of a patent-infringement ruling that threatens to halt sales of Word in its current form.
In May, a jury ordered Microsoft to pay $200m (£120m) for infringing on a patent held by Canada's i4i. Earlier this month, a federal judge increased that monetary award and also issued an injunction barring sales of Word that include the custom XML code found to infringe on i4i's patents.
"We believe the court erred in its interpretation and application of the law in this case and look forward to the 23 September hearing before the US Court of Appeals," Microsoft spokesman Kevin Kutz said in a statement.
In its papers, Microsoft makes a number of arguments for overturning the infringement finding, saying the judge made several procedural errors and failed to live up to his role as "gatekeeper".
"In patent cases, even more than most, the trial judge's role as a gatekeeper is crucial," Microsoft argued in its appeal. "As gatekeeper, the judge must define the metes and bounds of a patent through claim construction and then ensure that the evidence presented by the parties' numerous experts is both reliable and rooted in the facts of the case at hand.
"And after the jury has rendered its verdict, it is the judge who, before allowing that verdict to become an enforceable judgment, must ensure that the verdict is adequately supported by the evidence and supportable under the law... This case stands as a stark example of what can happen in a patent case when a judge abdicates those gatekeeping functions."
For its part, i4i has praised the ruling and said that it is not seeking to torpedo Word, but does want the infringing custom XML code removed.
"We're not seeking to stop Microsoft's business and we're not seeking to interfere with all the users of Word out there," i4i chairman Loudon Owen told ZDNet UK's sister site, CNET News.com, earlier this month.
In a statement on Wednesday, Owen called Microsoft's document "extraordinary".
"It captures the hostile attitude of Microsoft toward inventors who dare to enforce patents against them," Owen said. "It is also blatantly derogatory about the court system."
Owen said the company is counting on the court system to help it prevail even in the face of Microsoft's massive legal firepower.
"We do not have the gargantuan financial resources of Microsoft, but i4i has the protection of fairness under the US justice system. Microsoft is not above the law. It cannot privately expropriate i4i's patented invention."
Owen said i4i's response brief is due to be filed by 7 September. "We firmly believe the decision of the jury and judge in the United States District Court for the Eastern District of Texas was correct on the facts and we shall prevail on appeal," Owen said.
The appeals court has set a 23 September hearing to weigh an appeal of the case and potentially hold off the injunction, which is slated to go into effect in October.
In addition to pursuing its appeal, Microsoft has other options including creating a technical workaround, removing the XML function, or reaching a settlement with i4i.
