In a 150-page document, the company will try to convince an appeals court to overturn a lower court ruling that would split the software giant into two parts. US district judge Thomas Penfield Jackson handed the Department of Justice a victory in June when he ruled a breakup was the best remedy for a company that he said had illegally leveraged its monopoly to move into other markets. Microsoft immediately appealed, and now the US Court of Appeals for the District of Columbia will decide whether to let Jackson's ruling stand. In its opening brief, Microsoft will argue that it didn't break the law and should not be broken up. Microsoft is expected to elaborate on many of the arguments from earlier filings, in particular, that it did not prevent Netscape from marketing its Web browser. The assertions probably will mirror earlier arguments that urged a delay of the breakup until the appeal was resolved. The company maintains Jackson erred in ignoring Microsoft's arguments that consumers benefited from a free browser. It also argued that the combination of Internet Explorer (IE) and Windows software provided users with features unavailable to them in a non-Microsoft browser. Microsoft attorneys have relied heavily on one of Judge Jackson's few rulings in its favour when he said Microsoft's exclusive deals with PC makers had not kept Netscape from marketing its browser. The company also will probably cite a previous District of Columbia appeals court ruling overturning Judge Jackson's order prohibiting Microsoft from bundling IE and Windows. "How could you say that adding Internet technology wasn't the right thing to do?" asked Microsoft spokesman Jim Cullinan. Still, it appears Microsoft will challenge Jackson's findings of fact, which declared the company a monopolist. It's extremely difficult to get such findings overturned because appeals courts traditionally defer to lower court judges on factual matters and concentrate on legal issues. But Microsoft has repeatedly challenged Jackson's document in filings and interviews following its release. Microsoft also is expected to question Judge Jackson's conduct during the trial. In past filings, company attorneys have argued that Judge Jackson was biased against Microsoft and that he failed to provide them with an adequate arena to present their case. They've also accused Jackson of mishandling the case and applying antitrust laws too broadly. Once Microsoft files its brief, the DoJ has until 12 January to respond. Microsoft then has another chance to reply. However, the two sides are not scheduled to meet in court until 26 and 27 February, when attorneys are scheduled to present oral arguments. Usually, only three jurists hear appeals. But, in this case, the court already has agreed to hear arguments with a full panel of judges present. Some legal experts think Microsoft has a better chance with the full panel since most of the judges are conservative. The appeals court had considered calling in a technical expert to explain some computing basics to the judges, but that plan was scrapped in response to criticism from both sides. The court is accepting friend-of-the-court briefs from parties with stakes in the case, however. Microsoft supporters, including the Association for Competitive Technology, are also subject to the Monday deadline. Supporters of the Department of Justice decision, including America Online and the Software and Information Industry Association, have until 12 January to file their briefs. Even with an expedited schedule, the Microsoft case has dragged on for years. It was first filed in May of 1998. After months of sometimes-lively testimony from Microsoft employees and foes, Jackson issued his searing findings of fact -- which called Microsoft an abusive monopolist -- in November 1999. In June, after settlement talks fell through, Jackson ordered Microsoft to be split into two companies, one that would sell operating systems, the other devoted to applications and Internet services. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet News forum. Take me to the DoJ/Microsoft special. Let the editors know what you think in the Mailroom. And read what others have said.