The Redmond, Washington-based company asked the US Court of Appeals for the District of Columbia Circuit to readdress the finding that combining the Internet Explorer Web browser with Microsoft's Windows operating system violated antitrust law.
"Through this petition we are making a good-faith attempt to seek clarification on the issue of commingling," the company said in a statement. "This issue is important not only to Microsoft, but the industry as a whole, so we are asking for the court's guidance on this matter."
The company said it "believes there is no basis for the District Court's finding on commingling" and is "requesting the appeals court to review the record once more."
Microsoft's 12-page petition comes just a few days after the government asked the Court of Appeals to move the case forward without waiting for any petition for rehearing. Microsoft had 10 days to respond to that request.
In its 125-page ruling, the appeals court upheld eight separate claims that Microsoft violated the 1890 Sherman Antitrust Act. The ruling on commingling of code was one of the most devastating aspects of the appeals court decision, say legal experts.
"The Court of Appeals found there were certain anticompetitive acts from Microsoft's combining Internet Explorer with Windows 95 and 98," said Rich Gray, a Silicon Valley attorney closely following the trial.
"We conclude that such commingling has an anticompetitive effect," the ruling states. "The commingling deters (PC makers) from preinstalling rival browsers, thereby reducing the rivals' usage share and, hence, developers' interest in rivals' APIs (application programming interfaces) as an alternative to the API set exposed by Microsoft's operating system."
While Microsoft had argued that combining Internet Explorer with Windows was a procompetitive act offering benefits to users, the appeals court disagreed.
"When you write your code in such a way as to make it more difficult for competing technologies to compete with the operating system, and you're a monopolist, that's an act of monopoly maintenance," Stanton said.
Gray said Microsoft has good reason to oppose the commingling ruling because it affects potential product design and "opens a huge can of worms for Microsoft. What they are saying is Microsoft does not have unfettered discretion to do whatever they want with the design of their products. In their capacity as a monopolist, the court can second-guess them."