(FORTUNE Magazine) – After a somnolent decade, the antitrust brigade is back with a vengeance -- as airlines, Ivy League universities, Arizona dentists, and Salomon Brothers, all of whom have been investigated by the Justice Department, can attest. So can the milk industry. Some of the biggest fines meted out in the current wave of antitrust prosecutions have been levied against Borden and other companies found guilty of conspiring to fix the prices schools pay for milk; they were fined a total of $25 million. (See table for a sampling of recent antitrust fines.) Meanwhile, any company that has tried to do a merger lately has become aware of antitrust's revival. The Justice Department unit filed 11 actions against proposed mergers in 1990 vs. five in 1989. This may seem small potatoes, but it is the highest number since 1973. In addition, the increase has sent a signal to companies who might otherwise have crossed the legal line. As a result, and with an eye toward the heavier penalties being assessed when wrongdoing is found, a dozen deals have been scotched or restructured. Says Stephen Axinn, head of antitrust at New York City's Skadden Arps Slate Meagher & Flom, a law firm that just laid off a bunch of M&A specialists: ''The days when you might do a little community service, the old slap on the wrist, are gone. We are talking real jail time here.'' Yes, we are. Congress has not only increased the annual budget for antitrust & work by 12% to $53 million but also has authorized far stiffer penalties for violations. Executives found guilty of involvement in a price-fixing scheme can now be fined up to $350,000 and spend up to one year behind the Big Wall. James F. Rill, 58, who took charge of antitrust in 1989, promises that there'll be no letup. Says he: ''The division's merger docket remains full, and we expect it to stay that way.'' Rill's next crusade: changing the laws that exempt ocean shipping and international air carriers from antitrust laws.

CHART: NOT AVAILABLE CREDIT: FORTUNE TABLE/SOURCE: U.S. DEPARTMENT OF JUSTICE CAPTION: ANTITRUST PENALTIES Carl Icahn's Aero controls TWA.