The oral arguments are expected to be lively, as the seven justices – who have received briefs from attorneys and supporters of both sides – use the debate to probe the soundness of the arguments, and to weigh them against US antitrust law.
Facing the threat of a court-ordered break-up Microsoft appealed the case last year, which concluded with the divestiture remedy proposed in June by US district court judge, Thomas Penfield Jackson.
The appeal is designed to persuade the judges that, in offering its Internet Explorer (IE) browser together with its Windows operating system in 1998, Microsoft was neither anti-competitive, nor was the move harmful to consumers.
Richard Urowsky - who has argued twice on Microsoft's behalf - will again argue that, when IE was integrated with Windows, the result was better functionality and increased competition in the browser market because the dominant product at the time, Netscape Navigator, was forced to improve its product and lower its price.
Urowsky is also expected to argue that splitting the company in two - one entity to run the operating systems business and the other to take over applications and other business lines - is too great a risk to take.
On the opposing side, DOJ attorneys Jeffrey Minear, senior litigation counsel, and David Frederick, assistant to the solicitor general, will argue that the appellate court should uphold Jackson's verdict and his proposed break-up of the company, a remedy the DOJ sought.
Minear and Frederick will argue that Jackson correctly determined that Microsoft violated US antitrust law and that it "placed an oppressive thumb" on the scales of competition in order to guarantee its continued dominance in the operating system market and that its "tying" of IE to Windows was illegal and of no benefit to consumers.
As indicated in briefs filed in support of the government, the DOJ lawyers are expected to argue that Microsoft "simply did not care about the requirements of federal antitrust law" and believed it could outspend and outlast the government in court.
In the days leading up to oral arguments, supporters of the DOJ, including Kenneth Starr, known for his role as the government's special prosecutor in the Bill Clinton-Monica Lewinsky sex scandal, set the stage for the courtroom drama. Starr, who was hired by the Project to Promote Competition in the Digital Age (ProComp) to write a brief supporting the DOJ, was formerly a justice on the appellate court, which he described as "very bright, energetic and able".
During a conference call on Friday, Starr said: "I think the judges will be very attentive and focused on the facts. There's going to be a very deferential view toward the fact-finding in which the judge engaged. The record is the record and it's very strong. It will be very influential with this court."
In another conference call on Friday, Jonathan Zuck, executive director of the Association for Competitive Technology, which supports Microsoft's side in the case, said Microsoft is: "a company that competes hard and succeeds in the marketplace, while continuing to innovate. It faces competition every day, most notably from the Linux operating system, which continues to advance," he said.
The court will dedicate a portion of the oral arguments on Tuesday to Jackson's conduct since he finished his work on the case. Among the questions it will explore are the "extrajudicial statements" made by Jackson, including an interview with The New Yorker magazine in which he compared Microsoft Chairman and Chief Software Architect Bill Gates to Napoleon.
The appeals court is expected to rule sometime in the second quarter. Gates has expressed confidence that the appellate court will overturn the district court ruling.