Among many reasons for concern about the New York City ban on large servings of sugary beverages is the rule’s arbitrary nature and associated questions about its likely efficacy. This point is well made in a lawsuit filed Oct. 12 challenging the New York City Board of Health’s authority to issue the rule, which becomes effective in mid-March 2013.

The plaintiffs, a diverse group including the American Beverage Association and a local Teamsters union, note that the rule will not affect drinks that contain at least 50% milk, or fruit or vegetable juices that contain no added sugar. Making their case based on economic fairness, they note grocery stores and convenience stores will remain unregulated.

“Laden with exceptions, exclusions and loopholes, the ban draws lines and picks among businesses winners and losers based transparently on economic, political and social concerns ...,” the lawsuit said. For example, they note the rule imposes no limits on alcoholic beverages or certain milk or soy-based milk substitutes. Restaurants or bars would be forbidden from serving a 20-oz Coke, but they would be allowed to serve a 20-oz rum and Coke. Neighborhood diners would be permitted to sell 800-calorie milk shakes but forbidden from serving 240-calorie, 20-oz soft drinks.

It’s clear that bans such as those imposed by Mayor Bloomberg are modeled on smoking restrictions that many consider effective, but the lawsuit nicely demonstrates the degree to which the tobacco model breaks down when applied to the much more complicated world of food and drink. No one would argue that drinking a 48-oz serving of sugar-sweetened cola each morning is a formula for good health. But solving as thorny an issue as the proliferation of obesity will require better thinking than waging again “the last war,” the one aimed at curbing smoking.