It was like making an obscene gesture at a cop after being ticketed for speeding.

In 1994, Microsoft Corp. promised the Justice Department that it would end practices the government said were choking competition in the computer software industry. Company Chairman Bill Gates then made a defiant prediction about how the agreement would affect the computer giant's business style: "None of the people who run Microsoft's seven divisions are going to change what they do or think or forecast. Nothing. Nothing," he said.

Now that the Justice Department is seeking a $1 million-a-day fine against Microsoft for violating terms of that agreement, Gates's machismo seems like a less-than-brilliant public relations gambit. Nobody believes that Justice has sought the fine out of pique, but lawyers in the agency's antitrust division at the time were said to be furious about Gates's comments.

"It was foolish and provocative," said one Justice attorney, who did not want to be identified. "It was like saying, I'm going to break the law. Catch me if you can.' "

Chest thumping is only one of the many faux pas committed each year by companies negotiating with the Justice Department and the Federal Trade Commission, the two agencies charged with ensuring fair competition between U.S. companies.

Veterans of the game say that corporations and their lawyers often forget that antitrust law, especially as it is practiced in Washington, is both science and art, a few parts data and a few parts diplomacy. Marshaling persuasive arguments about econometrics and arcana like market definitions is most of the battle, though not all of it.

"All human processes have a dimension of art to them and antitrust is no different," said Joel Klein, head of Justice's antitrust division.

Over the years, many companies with antitrust matters pending have bungled their delicate minuet with the government. Here's a taxonomy of the more memorable errors: * Offending agency staffers.

A surprising number of companies infuriate agency staffers by calling them nitwits or issuing threats about the courtroom whipping they'll get if a case goes to trial. The hope, apparently, is that agency staffers can be bullied into backing off. Generally, this tactic fails.

"People go in thinking that they're dealing with a caricature government employee, someone lazy and stupid who can be buffaloed," said Joe Sims, a former Justice antitrust attorney who is now in private practice. "Those who come in with that attitude tend to leave with a lot of boot burns on their rear end."

The bravado approach backfired spectacularly in a recent high-profile case involving the proposed Staples-Office Depot merger. As FTC lawyers were mulling the deal, Donald Kempf Jr., one of the attorneys hired by Office Depot Inc., gruffly belittled FTC lawyers for asking what he called stupid questions, said Robert Doyle Jr., an FTC attorney who worked on the case and recently left for private practice. On several occasions, Kempf made a bold prediction about what would happen if the government took the case to trial: "I'm going to kick your {rear}," he said.

Kempf, a 60-year-old ex-Marine and partner at Chicago's Kirkland & Ellis, denies issuing the challenge in precisely those terms.

"I might have said, If we go to court, I will try to kick your {rear},' " Kempf said. "I'm a trial lawyer who's been around a long time and one thing you never do in this business is go in predicting victory."

Further, Kempf denied that he was condescending with FTC lawyers. But some lower-level staffers apparently were so peeved by Kempf's attitude that they began logging extra hours just to beat him. One told American Lawyer magazine, "He had so little respect and treated us so poorly. Every night when I wanted to go home, I said, No. This hour is for Donald Kempf.' "

The added effort apparently paid off. In July, a federal judge handed Kempf a very public defeat by blocking the Staples-Office Depot deal, concurring with the FTC that the merger was anti-competitive. Does Kempf have any regrets about the way he handled the case?

"No" he said. "My only regret is that we didn't win." * Caving in.

On the other hand, a little bluster is not always a bad idea. If a company isn't prepared to litigate its case -- or at least say so -- it's likely to get pushed around, say veterans of both agencies. Government lawyers, they point out, are paid a pittance compared with those in private practice, so their glory is measured by the number of deals they block or alter rather than the size of their paychecks.

"These agencies want scalps and if you seem too eager to offer up your scalp, they'll take it," said one former FTC attorney. "There's really no good reason to tell the government, If you block us, we'll just walk away.' That's like a sheep offering up its neck to a wolf." * Playing hide-the-merger.

Some corporations won't even bother to send in a brass-knuckled litigator. Instead, they simply merge and keep the news to themselves, or at least they don't share it with the government. To antitrust enforcers, this is a big no-no, and the repercussions once the deal is discovered are often very expensive.

Sara Lee Corp., for instance, in 1991 acquired Reckitt & Colman PLC, a shoe-care company based in England that competed against one of the dessert maker's subsidiaries, Kiwi Brands Inc. Sara Lee consummated the $25.8 million deal without alerting the government, the FTC alleged.

The commission not only undid the merger it fined Sara Lee $3.1 million in penalties for its failure to notify -- the largest-ever penalty of its kind.

"The case demonstrates that blatant attempts to avoid antitrust review of large mergers will result in a strong government response," William J. Baer, director of the FTC's Bureau of Competition, said in a press release last year. * Jumping the gun.

Sometimes, a company will make the necessary filings, but will start merging before it wins approval. Firms sometimes kick-start the process of combining the companies -- divvying up customers or colluding on prices or drafting new floor plans.

That, too, is verboten. Torrington Co., a maker of needle-rollers, learned that lesson when it bought Universal Bearings Inc. The FTC alleged in 1991 that the companies took steps toward consolidation before getting the necessary thumbs up, which effectively "constrained competition by fixing or stabilizing prices," according to the agency. The company signed a consent decree essentially promising that in the future, it would wait for a go sign before proceeding. It was, however, allowed to consummate the deal. 8 Calling Congress for help.

Corporations try this all the time, government attorneys said. A deal appears iffy or is about to be scuttled, so executives ask lawmakers to breathe on the FTC or the Justice Department. Usually, this ends up sparking skepticism, according to Kevin Arquit, an antitrust attorney and former director of the FTC's Bureau of Competition.

Typically what happens, Arquit said, is that a senator writes a perfunctory letter to the agency, pointing out that the deal is good for the economy and ought to be approved. But wary of seeming overly meddlesome -- remember how far that got the five lawmakers who intervened on behalf of S&L operator Charles Keating? -- the senator won't press much further. The agency staffers recognize this, and they typically send back a slightly modified form letter.

"Now, though, the staff is irked and perhaps they've got the impression that the company is unwilling to rely on the merits of its case," Arquit said.

Alliant Techsystems Inc., an ammunition maker, tried the "call Congress" route in 1992 when it sought approval to merge with Olin Corp.

"They had lots of senators and Congress members write the staff," said a former FTC attorney who worked on the issue. "As with all these efforts, it just ticked everyone off. We blocked them and then went to court and won." CAPTION: Donald Kempf Jr., who represented Office Depot Inc. in its attempt to merge with Staples, offended lawyers at the FTC by belittling their questions, they said. ec