What if restaurants throughout this country were too scared of a lawsuit to sell foods deemed fattening? It's not a far-fetched possibility, at least if a misguided gaggle of lawyers, legislators and researchers get their way.

Chicago is the latest focal point in a movement to create a slimmer America. Alderman Edward Burke this June proposed a citywide ban on the use of cooking with oils containing artificial trans fatty acids in restaurants that do at least $20 million a year worth of business. Establishments not in compliance would face fines ranging from $200 to $1,000 per day.

"We have to be very careful when we start telling everybody how to live their lives," cautioned Mayor Richard M. Daley. The mayor perhaps is making up for keeping a low profile in the face of recent bans enacted by the Board of Aldermen on smoking in restaurants and bars and on the selling of foie gras (a liver delicacy).

Elsewhere, dozens of states either have introduced or passed legislation aimed at curbing obesity. Measures include restricting advertising to children; requiring schools to provide parents with information about student body mass index; requiring schools to provide diabetes screening; mandating insurance coverage for obesity prevention and treatment; and establishing nutrition education programs. A University of Baltimore-affiliated think tank, the Schaefer Center for Public Policy, has created an annual "Obesity Report Card" to keep the heat on states to do more.

Granted, there never will be a shortage of people who, lacking in impulse control, prefer to gorge themselves without regard to health consequences. But to use that as a pretext to limit the range of pleasures available to all of us has an unpleasant ring of familiarity. Prohibition operated on this very premise: Let us combat the temptation to take an activity to excess by banning the activity outright.

Don't bother telling our latter-day Prohibitionists about the necessity of self-control. Whether the object of their wrath is food or alcohol, such talk merely serves as a cover for the irresponsible pursuit of profit.

For a good decade or more, Kelly Brownell, a paunchy Yale psychologist and top adviser to the deceptively effective Washington, D.C.-based Center for Science in the Public Interest, has called for punitive taxes on unhealthy food. "I recommend we develop a militant attitude about the toxic food environment, like we have about tobacco," he has written in CSPI's Nutrition Action Healthletter.

The plaintiff's bar, ever searching for victims to represent, has been exercising its own militancy. In August 2002, lawyers for Ashley Pelman, an overweight adolescent girl from the Bronx, N.Y., and other class-action plaintiffs, sued McDonald's, charging the corporation with deceptive marketing and advertising of "addictive" food. U.S. District Judge Robert Sweet dismissed the case early the following year, arguing, "If customers know the risks, they cannot blame McDonald's if they, nonetheless, choose to satiate their appetite with a surfeit of supersized McDonald's products."

If only he had left things at that.

Unfortunately, Judge Sweet also offered the plaintiffs advice on how to remedy their suit, emphasizing that McDonald's customers should have access to more thorough information. Predictably, Pelman's lawyer, Samuel Hirsch, two years later filed an amended complaint, albeit on narrower grounds. John "Sue the Bastards" Banzhaf, a renowned George Washington University law professor and adviser to the plaintiffs, is hopeful Hirsch will discover documents embarrassing to the corporation.

For the record, in a separate case several years ago some of Banzhaf's students took McDonald's to court, winning a $12.5 million judgment from the company, plus a public apology for claiming its french fries were cooked in pure vegetable oil. He knows which side his bread is buttered.

Such outcomes suggest almost limitless opportunities for creative pleading. Why, after all, stop at punishing the sale of fatty foods? Why not prohibit any activity that contributes to obesity?

New York State Assemblyman Felix Ortiz (D) already has this bright idea. A few years ago the Brooklyn legislator proposed six separate bills that would have slapped high taxes on the sale of fatty foods, movie tickets, video games, DVD rentals and other items ostensibly promoting sedentary living. The projected extra $50 million a year in revenue, he argued, could be earmarked for public exercise and nutrition programs.

In the face of such zealotry, thankfully, are signs of resistance. Nearly a year ago the House of Representatives passed the Personal Responsibility in Food Consumption Act (H.R. 554). This measure would shield food distributors and restaurants from civil liability for obesity-related claims. The Senate, with typical glacially-paced deliberation, has yet to act on its own companion measure (S. 908). More promisingly, roughly two dozen states to date have banned obesity lawsuits against restaurants.

Few would dispute obesity is a real and growing problem. The Centers for Disease Control has estimated that 44 million Americans were clinically obese in 2001, a 74 percent increase over the figure for 1991. And the U.S. Surgeon General estimated early this decade that nearly 10 percent of the nation's health care expenditures -- $117 billion annually -- are attributable to obesity and/or physical inactivity. The public tab for treating diabetes, heart disease, stroke, kidney failure and other obesity-related complications is enormous, especially for patients without insurance.

But instead of getting people to slim down by discovering villains, there's a better avenue for action. It's called the market.

People, by nature, tend to want to live as long as they can. And they have a tendency to seek information enabling them to do this. In recent decades, there has been a welcome explosion of preventive health care information available through magazines, the Internet, diet books, exercise courses and employer-sponsored wellness programs. Smart consumers tend to read up on these things.

Restaurants know it's a different world, too. That's why family-style chains such as Applebee's and T.G.I. Friday's have devoted parts of their menus to accommodating the calorie-conscious. Fast-food chains such as Subway and Baja Fresh openly tout themselves as healthy low-fat alternatives to their competitors. Even big, bad McDonald's has adjusted to the new realities, phasing out its supersized portions and introducing items such as salads and yogurt parfaits.

The campaign to punish purveyors of "toxic" foods, however, works against such tendencies. John Banzhaf, Felix Ortiz, Kelly Brownell and like-minded activists might deny it, but they harbor a deep mistrust of most people's ability to exercise sound judgment. The "social responsibility" they would impose upon restaurants and other food retailers is a pricey ticket to individual irresponsibility.