Lawyer Kay Hunt asked the justices to reinstate a lawsuit claiming a 2002 agreement by bars to ban drink specials on weekend nights was an illegal price-fixing conspiracy. Her Minneapolis law firm represents drinkers who claim they were overcharged as a result of the ban.

"Here, you have a group of competitors that bound together to eliminate drink specials," she said. Their deal, she added, "constituted an unreasonable restraint of trade."

The court, which heard about 75 minutes of oral arguments on Wednesday, will decide whether to uphold lower courts' dismissal of the case or to reinstate it.

The bars, about half of those near the University of Wisconsin-Madison campus, announced in September 2002 they would voluntarily ban drink specials on Friday and Saturday nights after 8 p.m.

At the time, some city officials were threatening to ban drink specials altogether and university officials were pressuring bar owners to help reduce binge drinking among students.

Hunt's firm filed the suit in 2004 on behalf of UW-Madison students and other customers who sought "tens of millions of dollars" in damages for being forced to pay too much for their booze.

The bars withdrew the ban after the lawsuit was filed. A university-sponsored study also showed that serious alcohol-related crime continued to go up despite the policy.

A judge dismissed the case in 2005 and an appeals court upheld the decision last year. Both courts said the bars' action was exempt from antitrust laws because they were reacting to regulatory pressure from the city.

A lawyer representing the bars told the justices on Wednesday that both lower courts got it right.

"This wasn't some secret meeting of the bar owners," said Kevin O'Connor, a lawyer representing 20 bars and the Dane County Tavern League. "This was all initiated by the city."

O'Connor said the case, if allowed to move forward, would make it difficult for cities in this heavy-drinking state to regulate alcohol. Bar owners from La Crosse to Milwaukee will not work with regulators if they fear being hit with an antitrust lawsuit, he said.

Eric Wilson, a state lawyer representing UW-Madison, backed up that argument. He said the case was not about price fixing but about trying to combat dangerous drinking among college students.

"The bars tried to work with the city and the university to be part of the solution, rather than part of the problem," he said.

Justices did not indicate how they intend to rule and had tough questions for both sides. Chief Justice Shirley Abrahamson called the case "very difficult."

Bar owners should be applauded and not punished with a multimillion dollar lawsuit for helping the city with a major problem, she said. But on the other hand, government officials should not be allowed to "bully individuals or businesses to do things that are contrary to the law," she said.