Joel Klein's departure from the US Department of Justice is unlikely to have any significant impact on the Microsoft antitrust case, according to legal experts and trial watchers. The DoJ said the assistant attorney general would leave at the end of the month. In a statement, Klein said he would take time off before looking for a new job. Although Klein was head of the division that led the DoJ to victory against the software giant by winning a break-up order against the company, the now two-and-a-half-year old case has gained its own momentum and will continue on appeal. Attorneys for both sides already have outlined most of their arguments, positions that are unlikely to change upon Klein's resignation. What's more, legal experts cautioned against reading into the timing of Klein's departure, which comes as the Supreme Court is deciding whether to hear the appeal of the break-up or let a lower appeals court decide Microsoft's future. That's because it's not uncommon for political appointees to step aside as an administration change looms. Plus, Klein is much less involved in the Microsoft case than the staffers handling the day-to-day activities of the trial and appeals process. "It would have more of an impact if one of those who was up to their elbows in the case leaves," said one Silicon Valley attorney who's been monitoring the case closely but asked not to be named. Microsoft wouldn't comment on Klein's leaving. Warren Grimes, a former Federal Trade Commission staffer and professor at Southwestern University School of Law in Los Angeles, said an administration change would be more likely to affect the case. "Compared to a potential change in administration, there's not that much of an impact here," he said. Some speculate that a Republican administration under George W. Bush would be less likely to investigate large companies and block the megamergers that have been so prevalent in recent years. Though Bush has not commented specifically on the Microsoft case, he's said repeatedly that he favours innovation over litigation. Under Klein, the DoJ antitrust division has been one of the most active in the country's history, blocking the merger of Sprint Communications and MCI WorldCom and aggressively pursuing Microsoft. Though it's still on appeal and far from over, the sweetest victory so far for federal trustbusters has been the Microsoft case. "He's been a very successful head of the division," Grimes said. "I think he's left his mark." Take me to the DoJ/Microsoft special. What do you think? Tell the Mailroom. And read what others have said.