The company said last week that it also opposes a move to grant the case class-action status, court documents show.

The accuses of duping consumers by labeling its Windows Genuine Advantage (WGA) software a critical security update, and failing to tell them that WGA collected information from their PCs and frequently "phoned home" that data to its servers.

In June 2006, Microsoft began pushing WGA to Windows XP users via Windows Update, the company's default update service, as a "high priority" update that was automatically downloaded and installed to most machines. Shortly after that, Microsoft acknowledged that WGA transmitted information whenever a user logged on to Windows XP. Under pressure from an , it later reduced the frequency of the piracy checks.

Microsoft relies on WGA to detect bootlegged copies of Windows; if the software sniffs out a counterfeit, WGA posts constant nagging messages on the screen.

In documents filed with a Seattle federal court on Sept. 22, Microsoft asked that a request for class-action status -- a move that would open the case to millions of Americans, and open up Microsoft to significant damages if it loses -- be denied.