From the files of "While I was gone": More than 100 companies signed a letter supporting software development firm i4i in a patent case against Microsoft that the U.S. Supreme Court will hear.

i4i sued Microsoft for patent infringement in a $290 million case over an XML editing feature in Microsoft Word. Microsoft has already made permanent changes removing the feature in Word, but the company has appealed the case to the U.S. Supreme Court. Several large corporations sided with Microsoft in amicus briefs, including Google, Apple, Wal-Mart and Toyota.

On Dec. 22, 141 companies signed a letter to the Department of Justice in support of i4i's position. The companies included its own cadre of large corporations such as Amgen, Eli Lilly, Genentech, DuPont and Monsanto.

The letter said, "We are greatly concerned that a reversal of the lower court’s decision in this case could seriously weaken the presumption of validity that attaches to millions of patents in force in the United States today, thereby undermining longstanding investment-backed reliance interests that are critical for domestic job creation and economic growth, and for U.S. technological leadership internationally."

i4i declined to comment on the letter, which is addressed to the U.S. Attorney General and Acting Solicitor General, who would represent the U.S. government in the Supreme Court case.

Microsoft's appeal questions the standard of proof the jury used in a lower court to decide if Microsoft had infringed on i4i's intellectual property. The case is expected to be heard in 2011.

Here is the entire letter the companies wrote in support of i4i.

Here is our earlier Seattle Times story about the Supreme Court appeal. The court is expected to hear the case this year.

Update 1:45 p.m.

In response to the letter of support for i4i's case, Microsoft said the case is about innovation. "This case is certainly about protecting innovation. Innovation is harmed by bad patents," said Kevin Kutz, a company spokesman. "When bad patents can’t be challenged effectively, that’s when innovation is significantly at risk."