A Texas judge ruled Tuesday that Microsoft cannot sell one of its flagship products, Word, in the United States because of patent infringement.

Judge Leonard Davis, of the U.S. District Court for the Eastern District of Texas, ordered a permanent injunction that "prohibits Microsoft from selling or importing to the United States any Microsoft Word products that have the capability of opening .XML, .DOCX or DOCM files (XML files) containing custom XML," according to an announcement by the plaintiff, Toronto-based i4i Inc.

XML essentially is a programming language that allows users to customize the underlying format of their word-processing documents, for example, and makes them readable across different word-processing programs. The ability to read and write XML documents is an integral feature of Microsoft Word.

In its complaint (PDF), i4i alleges Microsoft willingly violated its 1998 patent (No. 5,787,449) on a method for reading XML. The company, whose Web site advertises that users can "Create and edit XML content in Microsoft Word," helps clients work with XML.

i4i filed the lawsuit in March 2007, seeking an injunction and damages. The Eastern District of Texas is known for being a haven for patent litigation.

The injunction (PDF), which becomes effective in 60 days, prohibits Microsoft from selling future Word products that allegedly use the patented technology. It also enjoins Microsoft from testing, demonstrating, marketing or offering support for those future products.

Read the entire article at Seattle Pi.