America Online (AOL) and a trio of high-tech industry groups on Friday filed an amici curiae (friend of the court) brief asking the US Court of Appeals to uphold a US District Court judge's ruling to split Microsoft in two. The brief came on the same day as the US Department of Justice (DOJ) filed court papers in which it also defended the judge's order. US District Court Judge Thomas Penfield Jackson ruled June 7 that Microsoft should be broken into two parts after determining that the software giant had abused its monopoly in desktop operating systems to stifle competition. Microsoft appealed the order, which the judge stayed pending the outcome of the appeals process. Both Microsoft and the DOJ are set to engage in oral arguments at the appeals court on February 26 and 27. Along with AOL, the three IT bodies named in the amici curiae are the Computer & Communications Industry Association, the Software & Information Industry Association, and the Project to Promote Competition & Innovation in the Digital Age, also known as ProComp. ProComp's backers include Oracle and Sun Microsystems. Among the counsel for ProComp is former US Special Prosecutor Kenneth Starr, best known for his role as the government's special prosecutor in the Monica Lewinsky scandal that once threatened to topple US President Bill Clinton. The 25-page brief covers familiar ground already trodden by parties supporting the DOJ's case, such as Microsoft's violation of U.S. antitrust law as embodied in the Sherman Act and the company's harmful conduct towards its competitors, notably Netscape Communications, now part of AOL. The brief also calls for the upholding of Judge Jackson's conduct remedies against Microsoft, which are also being stayed while the appeal is underway. "Microsoft simply did not care about the requirements of federal antitrust law," the brief argues. "To reward Microsoft by freeing it from antitrust liability and a meaningful structural remedy would contravene clear Supreme Court precedent and send an extraordinarily harmful message to the business community." The software giant has butted heads with AOL before, notably voicing criticism over AOL's multi-billion US dollar merger with Time Warner, claiming it would harm competition. The merger was completed following the official go-ahead from the US Federal Communications Commission (FCC) late Thursday. AOL's brief can be read on the Web at Earlier Friday, the DOJ filed its own brief with the Appeals Court in which it defended both the judgement and the judge. The software vendor is due to submit its response to the DOJ's filing on Jan. 29. The hearings continue.