U.S. District Court Judge Thomas Penfield Jackson delivered his long-anticipated ruling in the Microsoft antitrust suit earlier this week. To no one's surprise, he ordered that the software giant be split in two. Microsoft will now appeal. The case is likely to take a special "fast track" to the U.S. Supreme Court, although the U.S. presidential election could yet influence the outcome. Yet no matter what the eventual result may be, there is little indication that Microsoft has learned much from this long-drawn-out ordeal. That is, in many ways, the cause of the entire mess.

Understanding the case is as simple as ABC. "A" is for abuse. In November, Judge Jackson issued preliminary findings of fact that Microsoft had monopoly power in the market for personal computer operating systems and used that power to harm consumers, computer manufacturers and others. An attempt to negotiate a settlement between the company, the U.S. government and state attorneys general that had joined the suit failed. In April, Mr. Jackson ruled that Microsoft broke U.S. antitrust law by abusing its monopoly in personal computer operating systems in a way that harmed consumers and intimidated competitors.

"B" is for breakup. After requesting that the two parties propose remedies, the judge ruled this week to split Microsoft in two. One company would own the operating system, which is currently installed on 80 percent of computers around the world. The other company would own Microsoft's other software and online businesses. In addition, the judge imposed restrictions on Microsoft's business conduct, such as forcing the company to give other software developers greater access to the Windows source code.