Redmond is seeking to overturn ruling that would force it to stop selling program in 60 days.
Microsoft on Tuesday formally appealed a judge's ruling that its Word application violates a patent held by a Canadian firm and that it therefore must stop selling the program within the U.S. in 60 days.
"If left undisturbed, the district court's injunction will inflict irreparable harm on Microsoft by potentially keeping the centerpiece of its product line out of the market for months," Microsoft said in a filing with the U.S. Court of Appeals in Washington, D.C.
Judge Leonard Davis, of U.S. District Court for Eastern Texas, last week ruled that Word infringes U.S. patent 5,787,449, which describes a "Method and System for Manipulating the Architecture and the Content of a Document Separately from Each Other," according to court records.
The patent is held by Toronto-based i4i, Inc. The company describes itself as a developer of "collaborative content solutions."
In its complaint, originally filed March 6, 2007, i4i claimed Microsoft violated its patent "by making, using, selling, offering to sell, and/or importing in or into the United States, without authority, Word 2003, Word 2007, .NET Framework, and Windows Vista."
Davis in his ruling said Microsoft Word "unlawfully infringed" on i4i's patent. He enjoined Redmond from selling or supporting new copies of Word 2003 and Word 2007 in the U.S. The ban would take effect in mid-October. Davis also ordered Microsoft to pay i4i more than $240 million in damages and costs.
Davis left an out for Microsoft. He noted that the infringing aspect of Word is its ability to open and read documents that contain custom XML—a form of the Extensible Markup Language format that businesses create to forge links between their back office data and PC applications like Word.
Davis said any version of Word that opens documents in plain text only, or which strips a document of custom XML through a process known as a transform, would be free from his order. That leaves the door open for Microsoft to issue a patch that alters Word's functionality in such a way as to circumvent the ban.
The stakes are high. Microsoft Office, which includes Word, accounted for more than $3 billion in worldwide sales in Microsoft's most recent fiscal year. Any prolonged ban on Microsoft Word sales could severely impact the company's top line.