WASHINGTON -- The antitrust laws that the U.S. government has wielded against Microsoft Corp. aim to protect consumers from monopolists and allow competition to flourish.

Judge Thomas Penfield Jackson's expected order Wednesday would, if it stands up on appeal, lead to the first breakup of a major U.S. corporation since AT&T agreed to spin off the "baby bell" regional telephone companies in 1982.The law on which the Microsoft case is based was written by Sen. John Sherman, an Ohio Republican and brother of Gen. William Tecumseh Sherman, to combat industrial giants in the oil, steel and railroad industries at the end of the 19th Century.

The 1890 Sherman Antitrust Act was most famously applied against John D. Rockefeller's Standard Oil, which was broken up into 34 companies after a Supreme Court decision in 1911.

The courts have found that companies can legally build monopolies by having better products than their competitors. But corporations cross the line if they use their power to muscle would-be rivals out of the marketplace or to extend their monopolies to new areas.

View Comments

Jackson found on Nov. 5 last year that Microsoft had illegally used its Windows monopoly in operating systems for personal computers to leverage market share in other areas. Jackson did not find that Microsoft created the monopoly illegally. He ruled again on April 3, saying Microsoft violated the antitrust law.

Judges who find companies guilty of "monopolization" under the Sherman act have done everything from imposing fines, to ordering changes in company practices, to splitting a monopoly into multiple companies.

In the AT&T case, the government said the company had monopolized the market for local and long-distance telephone service, along with equipment. AT&T was eventually broken up in 1984.

Government suits under the "monopolization" section of the law are relatively rare. The government spends most of its time reviewing mergers to make certain they are pro-competitive, often calling for divestitures as a condition of approval.

Join the Conversation
Looking for comments?
Find comments in their new home! Click the buttons at the top or within the article to view them — or use the button below for quick access.