Microsoft loses Word patent appeal

WASHINGTON — The Supreme Court upheld a patent infringement verdict that will cost Microsoft Corp. $300 million and already has forced changes in its Word software.

The justices yesterday unanimously rejected calls from Microsoft and its allies, including Apple Inc. and Google Inc., to overturn the award and make some patents more vulnerable to legal challenge.

The ruling is a victory for closely held I4i LP, which claimed in its 2007 lawsuit that its patented technology had been incorporated into Word, the word processing program used by 500 million people. The award is the largest ever upheld on appeal in a patent case.