"What is at stake here is the future of an open software industry and an open internet..."
Microsoft is facing a $1bn lawsuit from rival Sun Microsystems over what Sun alleges were deliberate efforts by the Redmond firm to develop incompatible software to force the Java programming language out of business.
In a statement, Sun counsel Michael Morris said: "Our suit seeks compensation from Microsoft for illegally impeding Sun's business and harming the Java platform."
"We believe sales of our server products have been impacted by Microsoft's anti-competitive behaviour ... What is at stake here is the future of an open software industry and an open internet," Morris added.
Sun is building its case on the anti-monopoly rulings made against Microsoft last year. In a similar move AOL Time Warner issued a lawsuit in January.
Both companies have long-standing grievances with Microsoft - Sun over Java and AOL Time Warner over what it saw as Microsoft's bullying tactics in the mid-1990s' browser war when Netscape lost out to Internet Explorer.
Both Sun and Netscape have sought legal redress against Microsoft in the past.
Sun boss, Scott McNealy has also been a long-standing critic of the legal process against Microsoft. McNealy described last year's settlement with the Department of Justice - which overturned Judge Jackson's decision to split Microsoft in two - as a "fix".